From 022c1417b6f8718200a52830a94f89163f4c5232 Mon Sep 17 00:00:00 2001
From: Ben Wallis <atomyc@gmail.com>
Date: Sat, 13 Nov 2021 20:46:45 +0000
Subject: [PATCH] EXP on kill is now shared between damage contributors. A
 "damage contributor" is either an individual entity, or a group - depending
 if the attacker is in a group. This means that not only does the "killing
 blow" no longer get 100% of EXP, but multiple groups and individuals all
 receive their fair share of EXP on death (assuming they are still within
 range of the entity when it dies).

Damage from a given individual or group only counts towards a kill for 10 minutes since that individual or group's last damage to the entity - after this period their damage contribution is removed. This avoids the list of damage contributors growing excessively large for an entity that does a lot of combat but never dies.

EXP sharing within groups is unchanged - the difference is simply that the input to this calculation may be less than 100% of the base EXP reward for the kill if other individuals or groups contributed damage.
---
 CHANGELOG.md                             |   1 +
 common/frontend/src/lib.rs               |   5 +
 common/net/src/msg/ecs_packet.rs         |  17 +-
 common/src/combat.rs                     |  69 +++++--
 common/src/comp/group.rs                 |   2 +-
 common/src/comp/health.rs                | 197 +++++++++++++++++--
 common/src/lib.rs                        |   1 +
 common/src/resources.rs                  |   2 +-
 common/state/src/plugin/module.rs        |  16 +-
 common/systems/src/beam.rs               |   2 +
 common/systems/src/buff.rs               |  32 ++-
 common/systems/src/melee.rs              |   2 +
 common/systems/src/projectile.rs         |   2 +
 common/systems/src/shockwave.rs          |   2 +
 common/systems/src/stats.rs              |   9 +-
 plugin/api/src/lib.rs                    |   8 +-
 server/src/cmd.rs                        |   2 +
 server/src/events/entity_manipulation.rs | 238 +++++++++++++++--------
 server/src/state_ext.rs                  |  16 +-
 server/src/sys/agent.rs                  |  26 ++-
 voxygen/src/audio/music.rs               |   7 +-
 voxygen/src/ecs/sys/floater.rs           |   6 +-
 voxygen/src/scene/figure/mod.rs          |   6 +-
 23 files changed, 512 insertions(+), 156 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 35ec7fd29b..20735e8a3e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -40,6 +40,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Tweaked critical chance of legendary weapons
 - Agents using fireball projectiles aim at the feet instead of the eyes
 - Explosions can now have a nonzero minimum falloff
+- EXP on kill is now shared based on damage contribution
 
 ### Removed
 
diff --git a/common/frontend/src/lib.rs b/common/frontend/src/lib.rs
index 1f5b389f48..7ebfa4585d 100644
--- a/common/frontend/src/lib.rs
+++ b/common/frontend/src/lib.rs
@@ -53,6 +53,11 @@ where
             .add_directive("veloren_common::trade=info".parse().unwrap())
             .add_directive("veloren_world::sim=info".parse().unwrap())
             .add_directive("veloren_world::civ=info".parse().unwrap())
+            .add_directive(
+                "veloren_server::events::entity_manipulation=info"
+                    .parse()
+                    .unwrap(),
+            )
             .add_directive("hyper=info".parse().unwrap())
             .add_directive("prometheus_hyper=info".parse().unwrap())
             .add_directive("mio::pool=info".parse().unwrap())
diff --git a/common/net/src/msg/ecs_packet.rs b/common/net/src/msg/ecs_packet.rs
index cac265fce0..09dcf509c2 100644
--- a/common/net/src/msg/ecs_packet.rs
+++ b/common/net/src/msg/ecs_packet.rs
@@ -1,6 +1,7 @@
 use crate::sync;
-use common::comp;
+use common::{comp, resources::Time};
 use serde::{Deserialize, Serialize};
+use specs::WorldExt;
 use std::marker::PhantomData;
 use sum_type::sum_type;
 
@@ -92,7 +93,12 @@ impl sync::CompPacket for EcsCompPacket {
             EcsCompPacket::Auras(comp) => sync::handle_insert(comp, entity, world),
             EcsCompPacket::Energy(comp) => sync::handle_insert(comp, entity, world),
             EcsCompPacket::Combo(comp) => sync::handle_insert(comp, entity, world),
-            EcsCompPacket::Health(comp) => sync::handle_insert(comp, entity, world),
+            EcsCompPacket::Health(mut comp) => {
+                // Time isn't synced between client and server so replace the Time from the
+                // server with the Client's local Time to enable accurate comparison.
+                comp.last_change.time = *world.read_resource::<Time>();
+                sync::handle_insert(comp, entity, world)
+            },
             EcsCompPacket::Poise(comp) => sync::handle_insert(comp, entity, world),
             EcsCompPacket::LightEmitter(comp) => sync::handle_insert(comp, entity, world),
             EcsCompPacket::Inventory(comp) => sync::handle_insert(comp, entity, world),
@@ -132,7 +138,12 @@ impl sync::CompPacket for EcsCompPacket {
             EcsCompPacket::Auras(comp) => sync::handle_modify(comp, entity, world),
             EcsCompPacket::Energy(comp) => sync::handle_modify(comp, entity, world),
             EcsCompPacket::Combo(comp) => sync::handle_modify(comp, entity, world),
-            EcsCompPacket::Health(comp) => sync::handle_modify(comp, entity, world),
+            EcsCompPacket::Health(mut comp) => {
+                // Time isn't synced between client and server so replace the Time from the
+                // server with the Client's local Time to enable accurate comparison.
+                comp.last_change.time = *world.read_resource::<Time>();
+                sync::handle_modify(comp, entity, world)
+            },
             EcsCompPacket::Poise(comp) => sync::handle_modify(comp, entity, world),
             EcsCompPacket::LightEmitter(comp) => sync::handle_modify(comp, entity, world),
             EcsCompPacket::Inventory(comp) => sync::handle_modify(comp, entity, world),
diff --git a/common/src/combat.rs b/common/src/combat.rs
index a554acd9e1..cd8d8c1e95 100644
--- a/common/src/combat.rs
+++ b/common/src/combat.rs
@@ -26,6 +26,7 @@ use rand::{thread_rng, Rng};
 
 use serde::{Deserialize, Serialize};
 
+use crate::{comp::Group, resources::Time};
 #[cfg(not(target_arch = "wasm32"))]
 use specs::{saveload::MarkerAllocator, Entity as EcsEntity, ReadStorage};
 #[cfg(not(target_arch = "wasm32"))]
@@ -53,6 +54,7 @@ pub enum AttackSource {
 pub struct AttackerInfo<'a> {
     pub entity: EcsEntity,
     pub uid: Uid,
+    pub group: Option<&'a Group>,
     pub energy: Option<&'a Energy>,
     pub combo: Option<&'a Combo>,
     pub inventory: Option<&'a Inventory>,
@@ -180,6 +182,7 @@ impl Attack {
         // maybe look into modifying strength of other effects?
         strength_modifier: f32,
         attack_source: AttackSource,
+        time: Time,
         mut emit: impl FnMut(ServerEvent),
         mut emit_outcome: impl FnMut(Outcome),
     ) -> bool {
@@ -222,10 +225,11 @@ impl Attack {
             );
             let change = damage.damage.calculate_health_change(
                 damage_reduction,
-                attacker.map(|a| a.uid),
+                attacker.map(|x| x.into()),
                 is_crit,
                 self.crit_multiplier,
                 strength_modifier,
+                time,
             );
             let applied_damage = -change.amount;
             accumulated_damage += applied_damage;
@@ -273,8 +277,9 @@ impl Attack {
                             if let Some(attacker_entity) = attacker.map(|a| a.entity) {
                                 let change = HealthChange {
                                     amount: applied_damage * l,
-                                    by: attacker.map(|a| a.uid),
+                                    by: attacker.map(|a| a.into()),
                                     cause: None,
+                                    time,
                                 };
                                 if change.amount.abs() > Health::HEALTH_EPSILON {
                                     emit(ServerEvent::HealthChange {
@@ -298,8 +303,9 @@ impl Attack {
                         CombatEffect::Heal(h) => {
                             let change = HealthChange {
                                 amount: *h * strength_modifier,
-                                by: attacker.map(|a| a.uid),
+                                by: attacker.map(|a| a.into()),
                                 cause: None,
+                                time,
                             };
                             if change.amount.abs() > Health::HEALTH_EPSILON {
                                 emit(ServerEvent::HealthChange {
@@ -408,8 +414,9 @@ impl Attack {
                         if let Some(attacker_entity) = attacker.map(|a| a.entity) {
                             let change = HealthChange {
                                 amount: accumulated_damage * l,
-                                by: attacker.map(|a| a.uid),
+                                by: attacker.map(|a| a.into()),
                                 cause: None,
+                                time,
                             };
                             if change.amount.abs() > Health::HEALTH_EPSILON {
                                 emit(ServerEvent::HealthChange {
@@ -433,8 +440,9 @@ impl Attack {
                     CombatEffect::Heal(h) => {
                         let change = HealthChange {
                             amount: h * strength_modifier,
-                            by: attacker.map(|a| a.uid),
+                            by: attacker.map(|a| a.into()),
                             cause: None,
+                            time,
                         };
                         if change.amount.abs() > Health::HEALTH_EPSILON {
                             emit(ServerEvent::HealthChange {
@@ -588,6 +596,41 @@ pub enum CombatRequirement {
     Combo(u32),
 }
 
+#[derive(Clone, Copy, Debug, Hash, Eq, PartialEq, Serialize, Deserialize)]
+pub enum DamageContributor {
+    Solo(Uid),
+    Group { entity_uid: Uid, group: Group },
+}
+
+impl DamageContributor {
+    pub fn new(uid: Uid, group: Option<Group>) -> Self {
+        if let Some(group) = group {
+            DamageContributor::Group {
+                entity_uid: uid,
+                group,
+            }
+        } else {
+            DamageContributor::Solo(uid)
+        }
+    }
+
+    pub fn uid(&self) -> Uid {
+        match self {
+            DamageContributor::Solo(uid) => *uid,
+            DamageContributor::Group {
+                entity_uid,
+                group: _,
+            } => *entity_uid,
+        }
+    }
+}
+
+impl From<AttackerInfo<'_>> for DamageContributor {
+    fn from(attacker_info: AttackerInfo) -> Self {
+        DamageContributor::new(attacker_info.uid, attacker_info.group.copied())
+    }
+}
+
 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, Serialize, Deserialize)]
 pub enum DamageSource {
     Buff(BuffKind),
@@ -673,10 +716,11 @@ impl Damage {
     pub fn calculate_health_change(
         self,
         damage_reduction: f32,
-        uid: Option<Uid>,
+        damage_contributor: Option<DamageContributor>,
         is_crit: bool,
         crit_mult: f32,
         damage_modifier: f32,
+        time: Time,
     ) -> HealthChange {
         let mut damage = self.value * damage_modifier;
         let critdamage = if is_crit {
@@ -697,8 +741,9 @@ impl Damage {
 
                 HealthChange {
                     amount: -damage,
-                    by: uid,
+                    by: damage_contributor,
                     cause: Some(self.source),
+                    time,
                 }
             },
             DamageSource::Falling => {
@@ -710,12 +755,14 @@ impl Damage {
                     amount: -damage,
                     by: None,
                     cause: Some(self.source),
+                    time,
                 }
             },
             DamageSource::Buff(_) | DamageSource::Other => HealthChange {
                 amount: -damage,
                 by: None,
                 cause: Some(self.source),
+                time,
             },
         }
     }
@@ -913,22 +960,22 @@ pub fn combat_rating(
     const SKILLS_WEIGHT: f32 = 1.0;
     const POISE_WEIGHT: f32 = 0.5;
     const CRIT_WEIGHT: f32 = 0.5;
-    // Normalzied with a standard max health of 100
+    // Normalized with a standard max health of 100
     let health_rating = health.base_max()
         / 100.0
         / (1.0 - Damage::compute_damage_reduction(Some(inventory), None, None)).max(0.00001);
 
-    // Normalzied with a standard max energy of 100 and energy reward multiplier of
+    // Normalized with a standard max energy of 100 and energy reward multiplier of
     // x1
     let energy_rating = (energy.base_max() + compute_max_energy_mod(Some(inventory))) / 100.0
         * compute_energy_reward_mod(Some(inventory));
 
-    // Normalzied with a standard max poise of 100
+    // Normalized with a standard max poise of 100
     let poise_rating = poise.base_max() as f32
         / 100.0
         / (1.0 - Poise::compute_poise_damage_reduction(inventory)).max(0.00001);
 
-    // Normalzied with a standard crit multiplier of 1.2
+    // Normalized with a standard crit multiplier of 1.2
     let crit_rating = compute_crit_mult(Some(inventory)) / 1.2;
 
     // Assumes a standard person has earned 20 skill points in the general skill
diff --git a/common/src/comp/group.rs b/common/src/comp/group.rs
index 4e124dfe04..3de7991fce 100644
--- a/common/src/comp/group.rs
+++ b/common/src/comp/group.rs
@@ -15,7 +15,7 @@ use tracing::{error, warn};
 //  - clients don't know which pets are theirs (could be easy to solve by
 //    putting owner uid in Role::Pet)
 
-#[derive(Copy, Clone, Debug, PartialEq, Serialize, Deserialize)]
+#[derive(Copy, Clone, Debug, Eq, Hash, PartialEq, Serialize, Deserialize)]
 pub struct Group(u32);
 
 // TODO: Hack
diff --git a/common/src/comp/health.rs b/common/src/comp/health.rs
index fbe7927b0e..e96abdeb6e 100644
--- a/common/src/comp/health.rs
+++ b/common/src/comp/health.rs
@@ -1,8 +1,11 @@
 #[cfg(not(target_arch = "wasm32"))]
 use crate::comp;
-use crate::{uid::Uid, DamageSource};
+use crate::DamageSource;
+use hashbrown::HashMap;
 use serde::{Deserialize, Serialize};
+use std::convert::TryFrom;
 
+use crate::{combat::DamageContributor, resources::Time};
 #[cfg(not(target_arch = "wasm32"))]
 use specs::{Component, DerefFlaggedStorage};
 #[cfg(not(target_arch = "wasm32"))]
@@ -12,16 +15,24 @@ use std::ops::Mul;
 /// Specifies what and how much changed current health
 #[derive(Clone, Copy, Debug, Serialize, Deserialize, PartialEq)]
 pub struct HealthChange {
+    /// The amount of the health change, negative is damage, positive is healing
     pub amount: f32,
-    pub by: Option<Uid>,
+    /// The the individual or group who caused the health change (None if the
+    /// damage wasn't caused by an entity)
+    pub by: Option<DamageContributor>,
+    /// The category of action that resulted in the health change
     pub cause: Option<DamageSource>,
+    /// The time that the health change occurred at
+    pub time: Time,
 }
 
 impl HealthChange {
-    pub fn damage_by(&self) -> Option<Uid> { self.cause.is_some().then_some(self.by).flatten() }
+    pub fn damage_by(&self) -> Option<DamageContributor> {
+        self.cause.is_some().then_some(self.by).flatten()
+    }
 }
 
-#[derive(Clone, Copy, Debug, Serialize, Deserialize)]
+#[derive(Clone, Debug, Serialize, Deserialize)]
 /// Health is represented by u32s within the module, but treated as a float by
 /// the rest of the game.
 // As a general rule, all input and output values to public functions should be
@@ -41,11 +52,14 @@ pub struct Health {
     /// Maximum is the amount of health the entity has after temporary modifiers
     /// are considered
     maximum: u32,
-    // Time since last change and what the last change was
-    // TODO: Remove the time since last change, either convert to time of last change or just emit
-    // an outcome where appropriate. Is currently just used for frontend.
-    pub last_change: (f64, HealthChange),
+    /// The last change to health
+    pub last_change: HealthChange,
     pub is_dead: bool,
+
+    /// Keeps track of damage per DamageContributor and the last time they
+    /// caused damage, used for EXP sharing
+    #[serde(skip)]
+    damage_contributors: HashMap<DamageContributor, (u64, Time)>,
 }
 
 impl Health {
@@ -98,12 +112,14 @@ impl Health {
             current: health,
             base_max: health,
             maximum: health,
-            last_change: (0.0, HealthChange {
+            last_change: HealthChange {
                 amount: 0.0,
                 by: None,
                 cause: None,
-            }),
+                time: Time(0.0),
+            },
             is_dead: false,
+            damage_contributors: HashMap::new(),
         }
     }
 
@@ -120,10 +136,39 @@ impl Health {
 
     #[cfg(not(target_arch = "wasm32"))]
     pub fn change_by(&mut self, change: HealthChange) {
+        let prev_health = i64::from(self.current);
         self.current = (((self.current() + change.amount).clamp(0.0, f32::from(Self::MAX_HEALTH))
             * Self::SCALING_FACTOR_FLOAT) as u32)
             .min(self.maximum);
-        self.last_change = (0.0, change);
+        let delta = i64::from(self.current) - prev_health;
+
+        self.last_change = change;
+
+        // If damage is applied by an entity, update the damage contributors
+        if delta < 0 {
+            if let Some(attacker) = change.by {
+                let entry = self
+                    .damage_contributors
+                    .entry(attacker)
+                    .or_insert((0, change.time));
+                (*entry).0 += u64::try_from(-delta).unwrap_or(0);
+                (*entry).1 = change.time
+            }
+
+            // Prune any damage contributors who haven't contributed damage for over the
+            // threshold - this enforces a maximum period that an entity will receive EXP
+            // for a kill after they last damaged the killed entity.
+            const DAMAGE_CONTRIB_PRUNE_SECS: f64 = 600.0;
+            self.damage_contributors.retain(|_, (_, last_damage_time)| {
+                (change.time.0 - last_damage_time.0) < DAMAGE_CONTRIB_PRUNE_SECS
+            });
+        }
+    }
+
+    pub fn damage_contributions(&self) -> impl Iterator<Item = (&DamageContributor, &u64)> {
+        self.damage_contributors
+            .iter()
+            .map(|(damage_contrib, (damage, _))| (damage_contrib, damage))
     }
 
     pub fn should_die(&self) -> bool { self.current == 0 }
@@ -139,20 +184,20 @@ impl Health {
         self.is_dead = false;
     }
 
-    // Function only exists for plugin tests, do not use anywhere else
-    // TODO: Remove somehow later
-    #[deprecated]
+    #[cfg(test)]
     pub fn empty() -> Self {
         Health {
             current: 0,
             base_max: 0,
             maximum: 0,
-            last_change: (0.0, HealthChange {
+            last_change: HealthChange {
                 amount: 0.0,
                 by: None,
                 cause: None,
-            }),
+                time: Time(0.0),
+            },
             is_dead: false,
+            damage_contributors: HashMap::new(),
         }
     }
 }
@@ -161,3 +206,123 @@ impl Health {
 impl Component for Health {
     type Storage = DerefFlaggedStorage<Self, IdvStorage<Self>>;
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::{
+        combat::DamageContributor,
+        comp::{Health, HealthChange},
+        resources::Time,
+        uid::Uid,
+    };
+
+    #[test]
+    fn test_change_by_negative_health_change_adds_to_damage_contributors() {
+        let mut health = Health::empty();
+        health.current = 100 * Health::SCALING_FACTOR_INT;
+        health.maximum = health.current;
+
+        let damage_contrib = DamageContributor::Solo(Uid(0));
+        let health_change = HealthChange {
+            amount: -5.0,
+            time: Time(123.0),
+            by: Some(damage_contrib),
+            cause: None,
+        };
+
+        health.change_by(health_change);
+
+        let (damage, time) = health.damage_contributors.get(&damage_contrib).unwrap();
+
+        assert_eq!(
+            health_change.amount.abs() as u64 * Health::SCALING_FACTOR_INT as u64,
+            *damage
+        );
+        assert_eq!(health_change.time, *time);
+    }
+
+    #[test]
+    fn test_change_by_positive_health_change_does_not_add_damage_contributor() {
+        let mut health = Health::empty();
+        health.maximum = 100 * Health::SCALING_FACTOR_INT;
+        health.current = (health.maximum as f32 * 0.5) as u32;
+
+        let damage_contrib = DamageContributor::Solo(Uid(0));
+        let health_change = HealthChange {
+            amount: 20.0,
+            time: Time(123.0),
+            by: Some(damage_contrib),
+            cause: None,
+        };
+
+        health.change_by(health_change);
+
+        assert!(health.damage_contributors.is_empty());
+    }
+
+    #[test]
+    fn test_change_by_multiple_damage_from_same_damage_contributor() {
+        let mut health = Health::empty();
+        health.current = 100 * Health::SCALING_FACTOR_INT;
+        health.maximum = health.current;
+
+        let damage_contrib = DamageContributor::Solo(Uid(0));
+        let health_change = HealthChange {
+            amount: -5.0,
+            time: Time(123.0),
+            by: Some(damage_contrib),
+            cause: None,
+        };
+        health.change_by(health_change);
+        health.change_by(health_change);
+
+        let (damage, _) = health.damage_contributors.get(&damage_contrib).unwrap();
+
+        assert_eq!(
+            (health_change.amount.abs() * 2.0) as u64 * Health::SCALING_FACTOR_INT as u64,
+            *damage
+        );
+        assert_eq!(1, health.damage_contributors.len());
+    }
+
+    #[test]
+    fn test_change_by_damage_contributor_pruning() {
+        let mut health = Health::empty();
+        health.current = 100 * Health::SCALING_FACTOR_INT;
+        health.maximum = health.current;
+
+        let damage_contrib1 = DamageContributor::Solo(Uid(0));
+        let health_change = HealthChange {
+            amount: -5.0,
+            time: Time(10.0),
+            by: Some(damage_contrib1),
+            cause: None,
+        };
+        health.change_by(health_change);
+
+        let damage_contrib2 = DamageContributor::Solo(Uid(1));
+        let health_change = HealthChange {
+            amount: -5.0,
+            time: Time(100.0),
+            by: Some(damage_contrib2),
+            cause: None,
+        };
+        health.change_by(health_change);
+
+        assert!(health.damage_contributors.contains_key(&damage_contrib1));
+        assert!(health.damage_contributors.contains_key(&damage_contrib2));
+
+        // Apply damage 610 seconds after the damage from damage_contrib1 - this should
+        // result in the damage from damage_contrib1 being pruned.
+        let health_change = HealthChange {
+            amount: -5.0,
+            time: Time(620.0),
+            by: Some(damage_contrib2),
+            cause: None,
+        };
+        health.change_by(health_change);
+
+        assert!(!health.damage_contributors.contains_key(&damage_contrib1));
+        assert!(health.damage_contributors.contains_key(&damage_contrib2));
+    }
+}
diff --git a/common/src/lib.rs b/common/src/lib.rs
index 01cd3e8dde..40464ae54c 100644
--- a/common/src/lib.rs
+++ b/common/src/lib.rs
@@ -13,6 +13,7 @@
     type_alias_impl_trait,
     extend_one
 )]
+#![feature(hash_drain_filter)]
 
 /// Re-exported crates
 #[cfg(not(target_arch = "wasm32"))]
diff --git a/common/src/resources.rs b/common/src/resources.rs
index 4a55d3b5c3..5b0061aa8b 100644
--- a/common/src/resources.rs
+++ b/common/src/resources.rs
@@ -9,7 +9,7 @@ use specs::Entity;
 pub struct TimeOfDay(pub f64);
 
 /// A resource that stores the tick (i.e: physics) time.
-#[derive(Copy, Clone, Debug, Default, Serialize, Deserialize)]
+#[derive(Copy, Clone, Debug, Default, Serialize, Deserialize, PartialEq)]
 pub struct Time(pub f64);
 
 /// A resource that stores the time since the previous tick.
diff --git a/common/state/src/plugin/module.rs b/common/state/src/plugin/module.rs
index 740bb32b0f..b7cdfec56e 100644
--- a/common/state/src/plugin/module.rs
+++ b/common/state/src/plugin/module.rs
@@ -268,12 +268,16 @@ fn retrieve_action(
                 RetrieveError::EcsAccessError(EcsAccessError::EcsEntityNotFound(e)),
             )?;
             Ok(RetrieveResult::GetEntityHealth(
-                *world.health.get(player).ok_or_else(|| {
-                    RetrieveError::EcsAccessError(EcsAccessError::EcsComponentNotFound(
-                        e,
-                        "Health".to_owned(),
-                    ))
-                })?,
+                world
+                    .health
+                    .get(player)
+                    .ok_or_else(|| {
+                        RetrieveError::EcsAccessError(EcsAccessError::EcsComponentNotFound(
+                            e,
+                            "Health".to_owned(),
+                        ))
+                    })?
+                    .clone(),
             ))
         },
     }
diff --git a/common/systems/src/beam.rs b/common/systems/src/beam.rs
index 5a1e0d75cb..cb5aabc8c9 100644
--- a/common/systems/src/beam.rs
+++ b/common/systems/src/beam.rs
@@ -210,6 +210,7 @@ impl<'a> System<'a> for Sys {
                                     AttackerInfo {
                                         entity,
                                         uid,
+                                        group: read_data.groups.get(entity),
                                         energy: read_data.energies.get(entity),
                                         combo: read_data.combos.get(entity),
                                         inventory: read_data.inventories.get(entity),
@@ -249,6 +250,7 @@ impl<'a> System<'a> for Sys {
                                 attack_options,
                                 1.0,
                                 AttackSource::Beam,
+                                *read_data.time,
                                 |e| server_events.push(e),
                                 |o| outcomes.push(o),
                             );
diff --git a/common/systems/src/buff.rs b/common/systems/src/buff.rs
index a99d26b3d6..47bff77b11 100644
--- a/common/systems/src/buff.rs
+++ b/common/systems/src/buff.rs
@@ -1,4 +1,5 @@
 use common::{
+    combat::DamageContributor,
     comp::{
         body::{object, Body},
         buff::{
@@ -6,17 +7,19 @@ use common::{
             Buffs,
         },
         fluid_dynamics::{Fluid, LiquidKind},
-        Health, HealthChange, Inventory, LightEmitter, ModifierKind, PhysicsState, Stats,
+        Group, Health, HealthChange, Inventory, LightEmitter, ModifierKind, PhysicsState, Stats,
     },
     event::{EventBus, ServerEvent},
-    resources::DeltaTime,
+    resources::{DeltaTime, Time},
     terrain::SpriteKind,
+    uid::UidAllocator,
     Damage, DamageSource,
 };
 use common_ecs::{Job, Origin, Phase, System};
 use hashbrown::HashMap;
 use specs::{
-    shred::ResourceId, Entities, Join, Read, ReadStorage, SystemData, World, WriteStorage,
+    saveload::MarkerAllocator, shred::ResourceId, Entities, Join, Read, ReadStorage, SystemData,
+    World, WriteStorage,
 };
 use std::time::Duration;
 
@@ -28,6 +31,9 @@ pub struct ReadData<'a> {
     inventories: ReadStorage<'a, Inventory>,
     healths: ReadStorage<'a, Health>,
     physics_states: ReadStorage<'a, PhysicsState>,
+    groups: ReadStorage<'a, Group>,
+    uid_allocator: Read<'a, UidAllocator>,
+    time: Read<'a, Time>,
 }
 
 #[derive(Default)]
@@ -209,9 +215,27 @@ impl<'a> System<'a> for Sys {
                                         ModifierKind::Additive => *accumulated,
                                         ModifierKind::Fractional => health.maximum() * *accumulated,
                                     };
+                                    let damage_contributor = by
+                                        .map(|uid| {
+                                            read_data
+                                                .uid_allocator
+                                                .retrieve_entity_internal(uid.0)
+                                                .map(|entity| {
+                                                    DamageContributor::new(
+                                                        uid,
+                                                        read_data.groups.get(entity).cloned(),
+                                                    )
+                                                })
+                                        })
+                                        .flatten();
                                     server_emitter.emit(ServerEvent::HealthChange {
                                         entity,
-                                        change: HealthChange { amount, by, cause },
+                                        change: HealthChange {
+                                            amount,
+                                            by: damage_contributor,
+                                            cause,
+                                            time: *read_data.time,
+                                        },
                                     });
                                     *accumulated = 0.0;
                                 };
diff --git a/common/systems/src/melee.rs b/common/systems/src/melee.rs
index 663cf6d5c5..d8f0a9ca9d 100644
--- a/common/systems/src/melee.rs
+++ b/common/systems/src/melee.rs
@@ -149,6 +149,7 @@ impl<'a> System<'a> for Sys {
                     let attacker_info = Some(AttackerInfo {
                         entity: attacker,
                         uid: *uid,
+                        group: read_data.groups.get(attacker),
                         energy: read_data.energies.get(attacker),
                         combo: read_data.combos.get(attacker),
                         inventory: read_data.inventories.get(attacker),
@@ -187,6 +188,7 @@ impl<'a> System<'a> for Sys {
                         attack_options,
                         1.0,
                         AttackSource::Melee,
+                        *read_data.time,
                         |e| server_emitter.emit(e),
                         |o| outcomes.push(o),
                     );
diff --git a/common/systems/src/projectile.rs b/common/systems/src/projectile.rs
index 5ccede22a4..1f0013d669 100644
--- a/common/systems/src/projectile.rs
+++ b/common/systems/src/projectile.rs
@@ -264,6 +264,7 @@ fn dispatch_hit(
                     .map(|(entity, uid)| AttackerInfo {
                         entity,
                         uid,
+                        group: read_data.groups.get(entity),
                         energy: read_data.energies.get(entity),
                         combo: read_data.combos.get(entity),
                         inventory: read_data.inventories.get(entity),
@@ -318,6 +319,7 @@ fn dispatch_hit(
                 attack_options,
                 1.0,
                 AttackSource::Projectile,
+                *read_data.time,
                 |e| server_emitter.emit(e),
                 |o| outcomes.push(o),
             );
diff --git a/common/systems/src/shockwave.rs b/common/systems/src/shockwave.rs
index fdf8d26613..2074d74aa7 100644
--- a/common/systems/src/shockwave.rs
+++ b/common/systems/src/shockwave.rs
@@ -192,6 +192,7 @@ impl<'a> System<'a> for Sys {
                             .map(|(entity, uid)| AttackerInfo {
                                 entity,
                                 uid,
+                                group: read_data.groups.get(entity),
                                 energy: read_data.energies.get(entity),
                                 combo: read_data.combos.get(entity),
                                 inventory: read_data.inventories.get(entity),
@@ -230,6 +231,7 @@ impl<'a> System<'a> for Sys {
                         attack_options,
                         1.0,
                         AttackSource::Shockwave,
+                        *read_data.time,
                         |e| server_emitter.emit(e),
                         |o| outcomes.push(o),
                     );
diff --git a/common/systems/src/stats.rs b/common/systems/src/stats.rs
index b4bb53e536..76536279bc 100644
--- a/common/systems/src/stats.rs
+++ b/common/systems/src/stats.rs
@@ -73,13 +73,6 @@ impl<'a> System<'a> for Sys {
         let mut server_event_emitter = read_data.server_bus.emitter();
         let dt = read_data.dt.0;
 
-        // Increment last change timer
-        healths.set_event_emission(false); // avoid unnecessary syncing
-        for mut health in (&mut healths).join() {
-            health.last_change.0 += f64::from(dt);
-        }
-        healths.set_event_emission(true);
-
         // Update stats
         for (entity, uid, stats, mut skill_set, mut health, pos, mut energy, inventory) in (
             &read_data.entities,
@@ -100,7 +93,7 @@ impl<'a> System<'a> for Sys {
                 entities_died_last_tick.0.push(cloned_entity);
                 server_event_emitter.emit(ServerEvent::Destroy {
                     entity,
-                    cause: health.last_change.1,
+                    cause: health.last_change,
                 });
 
                 health.is_dead = true;
diff --git a/plugin/api/src/lib.rs b/plugin/api/src/lib.rs
index 3794310313..b9562d0465 100644
--- a/plugin/api/src/lib.rs
+++ b/plugin/api/src/lib.rs
@@ -50,9 +50,11 @@ pub enum Action {
 /// ```
 /// Over this one:
 /// ```rust
+/// # use common::comp::Body;
+/// # use common::comp::body::humanoid;
 /// # use veloren_plugin_api::*;
 /// # let entityid = Uid(0);
-/// # fn retrieve_action(r: &Retrieve) -> Result<RetrieveResult, RetrieveError> { Ok(RetrieveResult::GetEntityHealth(Health::empty()))}
+/// # fn retrieve_action(r: &Retrieve) -> Result<RetrieveResult, RetrieveError> { Ok(RetrieveResult::GetEntityHealth(Health::new(Body::Humanoid(humanoid::Body::random()), 1))) }
 /// let life = if let RetrieveResult::GetEntityHealth(e) =
 ///     retrieve_action(&Retrieve::GetEntityHealth(entityid)).unwrap()
 /// {
@@ -75,9 +77,11 @@ pub enum Retrieve {
 ///
 /// Example:
 /// ```rust
+/// # use common::comp::Body;
+/// # use common::comp::body::humanoid;
 /// # use veloren_plugin_api::*;
 /// # let entityid = Uid(0);
-/// # fn retrieve_action(r: &Retrieve) -> Result<RetrieveResult, RetrieveError> { Ok(RetrieveResult::GetEntityHealth(Health::empty()))}
+/// # fn retrieve_action(r: &Retrieve) -> Result<RetrieveResult, RetrieveError> { Ok(RetrieveResult::GetEntityHealth(Health::new(Body::Humanoid(humanoid::Body::random()), 1)))}
 /// let life = if let RetrieveResult::GetEntityHealth(e) =
 ///     retrieve_action(&Retrieve::GetEntityHealth(entityid)).unwrap()
 /// {
diff --git a/server/src/cmd.rs b/server/src/cmd.rs
index 7963dd57a5..1117ed3a37 100644
--- a/server/src/cmd.rs
+++ b/server/src/cmd.rs
@@ -1021,10 +1021,12 @@ fn handle_health(
             .write_storage::<comp::Health>()
             .get_mut(target)
         {
+            let time = server.state.ecs().read_resource::<Time>();
             let change = comp::HealthChange {
                 amount: hp - health.current(),
                 by: None,
                 cause: None,
+                time: *time,
             };
             health.change_by(change);
             Ok(())
diff --git a/server/src/events/entity_manipulation.rs b/server/src/events/entity_manipulation.rs
index 46c6ef7894..cc7a199178 100644
--- a/server/src/events/entity_manipulation.rs
+++ b/server/src/events/entity_manipulation.rs
@@ -11,6 +11,7 @@ use crate::{
 };
 use common::{
     combat,
+    combat::DamageContributor,
     comp::{
         self, aura, buff,
         chat::{KillSource, KillType},
@@ -33,10 +34,20 @@ use common_state::BlockChange;
 use comp::chat::GenericChatMsg;
 use hashbrown::HashSet;
 use rand::Rng;
-use specs::{join::Join, saveload::MarkerAllocator, Builder, Entity as EcsEntity, WorldExt};
-use tracing::error;
+use specs::{
+    join::Join, saveload::MarkerAllocator, Builder, Entity as EcsEntity, Entity, WorldExt,
+};
+use std::{collections::HashMap, iter};
+use tracing::{debug, error};
 use vek::{Vec2, Vec3};
 
+#[derive(Hash, Eq, PartialEq)]
+enum DamageContrib {
+    Solo(EcsEntity),
+    Group(Group),
+    NotFound,
+}
+
 pub fn handle_poise(server: &Server, entity: EcsEntity, change: f32, knockback_dir: Vec3<f32>) {
     let ecs = &server.state.ecs();
     if let Some(character_state) = ecs.read_storage::<CharacterState>().get(entity) {
@@ -153,7 +164,7 @@ pub fn handle_destroy(server: &mut Server, entity: EcsEntity, last_change: Healt
     // If it was a player that died
     if let Some(_player) = state.ecs().read_storage::<Player>().get(entity) {
         if let Some(uid) = state.ecs().read_storage::<Uid>().get(entity) {
-            let kill_source = match (last_change.cause, last_change.by) {
+            let kill_source = match (last_change.cause, last_change.by.map(|x| x.uid())) {
                 (Some(DamageSource::Melee), Some(by)) => get_attacker_name(KillType::Melee, by),
                 (Some(DamageSource::Projectile), Some(by)) => {
                     get_attacker_name(KillType::Projectile, by)
@@ -178,25 +189,20 @@ pub fn handle_destroy(server: &mut Server, entity: EcsEntity, last_change: Healt
         }
     }
 
-    // Give EXP to the killer if entity had stats
+    // Award EXP to damage contributors
+    //
+    // NOTE: Debug logging is disabled by default for this module - to enable it add
+    // veloren_server::events::entity_manipulation=debug to RUST_LOG
     (|| {
-        let mut skill_set = state.ecs().write_storage::<SkillSet>();
+        let mut skill_sets = state.ecs().write_storage::<SkillSet>();
         let healths = state.ecs().read_storage::<Health>();
         let energies = state.ecs().read_storage::<Energy>();
         let inventories = state.ecs().read_storage::<Inventory>();
         let players = state.ecs().read_storage::<Player>();
         let bodies = state.ecs().read_storage::<Body>();
         let poises = state.ecs().read_storage::<comp::Poise>();
-        let by = if let Some(by) = last_change.by {
-            by
-        } else {
-            return;
-        };
-        let attacker = if let Some(attacker) = state.ecs().entity_from_uid(by.into()) {
-            attacker
-        } else {
-            return;
-        };
+        let positions = state.ecs().read_storage::<Pos>();
+        let groups = state.ecs().read_storage::<Group>();
 
         let (
             entity_skill_set,
@@ -205,37 +211,25 @@ pub fn handle_destroy(server: &mut Server, entity: EcsEntity, last_change: Healt
             entity_inventory,
             entity_body,
             entity_poise,
+            entity_pos,
         ) = match (|| {
             Some((
-                skill_set.get(entity)?,
+                skill_sets.get(entity)?,
                 healths.get(entity)?,
                 energies.get(entity)?,
                 inventories.get(entity)?,
                 bodies.get(entity)?,
                 poises.get(entity)?,
+                positions.get(entity)?,
             ))
         })() {
             Some(comps) => comps,
             None => return,
         };
 
-        let groups = state.ecs().read_storage::<Group>();
-        let attacker_group = groups.get(attacker);
-        let destroyed_group = groups.get(entity);
-        // Don't give exp if attacker destroyed themselves or one of their group
-        // members, or a pvp kill
-        if (attacker_group.is_some() && attacker_group == destroyed_group)
-            || attacker == entity
-            || (players.get(entity).is_some() && players.get(attacker).is_some())
-        {
-            return;
-        }
-        // Maximum distance for other group members to receive exp
-        const MAX_EXP_DIST: f32 = 150.0;
-        // TODO: Scale xp from skillset rather than health, when NPCs have their own
-        // skillsets
+        // Calculate the total EXP award for the kill
         let msm = state.ecs().read_resource::<MaterialStatManifest>();
-        let mut exp_reward = combat::combat_rating(
+        let exp_reward = combat::combat_rating(
             entity_inventory,
             entity_health,
             entity_energy,
@@ -245,63 +239,134 @@ pub fn handle_destroy(server: &mut Server, entity: EcsEntity, last_change: Healt
             &msm,
         ) * 20.0;
 
-        // Distribute EXP to group
-        let positions = state.ecs().read_storage::<Pos>();
+        let mut damage_contributors = HashMap::<DamageContrib, (u64, f32)>::new();
+        for (damage_contributor, damage) in entity_health.damage_contributions() {
+            match damage_contributor {
+                DamageContributor::Solo(uid) => {
+                    if let Some(attacker) = state.ecs().entity_from_uid(uid.0) {
+                        damage_contributors.insert(DamageContrib::Solo(attacker), (*damage, 0.0));
+                    } else {
+                        // An entity who was not in a group contributed damage but is now either
+                        // dead or offline. Add a placeholder to ensure that the contributor's exp
+                        // is discarded, not distributed between the other contributors
+                        damage_contributors.insert(DamageContrib::NotFound, (*damage, 0.0));
+                    }
+                },
+                DamageContributor::Group {
+                    entity_uid: _,
+                    group,
+                } => {
+                    // Damage made by entities who were in a group at the time of attack is
+                    // attributed to their group rather than themselves. This allows for all
+                    // members of a group to receive EXP, not just the damage dealers.
+                    let entry = damage_contributors
+                        .entry(DamageContrib::Group(*group))
+                        .or_insert((0, 0.0));
+                    (*entry).0 += damage;
+                },
+            }
+        }
+
+        // Calculate the percentage of total damage that each DamageContributor
+        // contributed
+        let total_damage: f64 = damage_contributors
+            .values()
+            .map(|(damage, _)| *damage as f64)
+            .sum();
+        damage_contributors
+            .iter_mut()
+            .for_each(|(_, (damage, percentage))| {
+                *percentage = (*damage as f64 / total_damage) as f32
+            });
+
         let alignments = state.ecs().read_storage::<Alignment>();
         let uids = state.ecs().read_storage::<Uid>();
         let mut outcomes = state.ecs().write_resource::<Vec<Outcome>>();
         let inventories = state.ecs().read_storage::<comp::Inventory>();
-        if let (Some(attacker_group), Some(pos)) = (attacker_group, positions.get(entity)) {
-            // TODO: rework if change to groups makes it easier to iterate entities in a
-            // group
-            let mut non_pet_group_members_in_range = 1;
-            let members_in_range = (
-                &state.ecs().entities(),
-                &groups,
-                &positions,
-                alignments.maybe(),
-                &uids,
-            )
-                .join()
-                .filter(|(entity, group, member_pos, _, _)| {
-                    // Check if: in group, not main attacker, and in range
-                    *group == attacker_group
-                        && *entity != attacker
-                        && pos.0.distance_squared(member_pos.0) < MAX_EXP_DIST.powi(2)
-                })
-                .map(|(entity, _, _, alignment, uid)| {
-                    if !matches!(alignment, Some(Alignment::Owned(owner)) if owner != uid) {
-                        non_pet_group_members_in_range += 1;
-                    }
 
-                    (entity, uid)
-                })
-                .collect::<Vec<_>>();
-            // Divides exp reward by square root of number of people in group
-            exp_reward /= (non_pet_group_members_in_range as f32).sqrt();
-            members_in_range.into_iter().for_each(|(e, uid)| {
-                if let (Some(inventory), Some(mut skill_set)) =
-                    (inventories.get(e), skill_set.get_mut(e))
-                {
-                    handle_exp_gain(exp_reward, inventory, &mut skill_set, uid, &mut outcomes);
+        let destroyed_group = groups.get(entity);
+
+        let within_range = |attacker_pos: &Pos| {
+            // Maximum distance that an attacker must be from an entity at the time of its
+            // death to receive EXP for the kill
+            const MAX_EXP_DIST: f32 = 150.0;
+            entity_pos.0.distance_squared(attacker_pos.0) < MAX_EXP_DIST.powi(2)
+        };
+
+        let is_pvp_kill =
+            |attacker: Entity| players.get(entity).is_some() && players.get(attacker).is_some();
+
+        // Iterate through all contributors of damage for the killed entity, calculating
+        // how much EXP each contributor should be awarded based on their
+        // percentage of damage contribution
+        damage_contributors.iter().filter_map(|(damage_contributor, (_, damage_percent))| {
+            let contributor_exp = exp_reward * damage_percent;
+            match damage_contributor {
+                DamageContrib::Solo(attacker) => {
+                    // No exp for self kills or PvP 
+                    if *attacker == entity || is_pvp_kill(*attacker) { return None; }
+
+                    // Only give EXP to the attacker if they are within EXP range of the killed entity
+                    positions.get(*attacker).and_then(|attacker_pos| {
+                        if within_range(attacker_pos) {
+                            debug!("Awarding {} exp to individual {:?} who contributed {}% damage to the kill of {:?}", contributor_exp, attacker, *damage_percent * 100.0, entity);
+                            Some(iter::once((*attacker, contributor_exp)).collect())
+                        } else {
+                            None
+                        }
+                    })
+                },
+                DamageContrib::Group(group) => {
+                    // Don't give EXP to members in the destroyed entity's group
+                    if destroyed_group == Some(group) { return None; }
+
+                    // Only give EXP to members of the group that are within EXP range of the killed entity and aren't a pet
+                    let members_in_range = (
+                        &state.ecs().entities(),
+                        &groups,
+                        &positions,
+                        alignments.maybe(),
+                        &uids,
+                    )
+                        .join()
+                        .filter_map(|(member_entity, member_group, member_pos, alignment, uid)| {
+                            if *member_group == *group && within_range(member_pos) && !is_pvp_kill(member_entity) && !matches!(alignment, Some(Alignment::Owned(owner)) if owner != uid) {
+                                Some(member_entity)
+                            } else {
+                                None
+                            }
+                        })
+                        .collect::<Vec<_>>();
+
+                    if members_in_range.is_empty() { return None; }
+
+                    // Divide EXP reward by square root of number of people in group for group EXP scaling
+                    let exp_per_member = contributor_exp / (members_in_range.len() as f32).sqrt();
+
+                    debug!("Awarding {} exp per member of group ID {:?} with {} members which contributed {}% damage to the kill of {:?}", exp_per_member, group, members_in_range.len(), *damage_percent * 100.0, entity);
+                    Some(members_in_range.into_iter().map(|entity| (entity, exp_per_member)).collect::<Vec<(Entity, f32)>>())
+                },
+                DamageContrib::NotFound => {
+                    // Discard exp for dead/offline individual damage contributors
+                    None
                 }
-            });
-        }
-
-        if let (Some(mut attacker_skill_set), Some(attacker_uid), Some(attacker_inventory)) = (
-            skill_set.get_mut(attacker),
-            uids.get(attacker),
-            inventories.get(attacker),
-        ) {
-            // TODO: Discuss whether we should give EXP by Player Killing or not.
-            handle_exp_gain(
-                exp_reward,
-                attacker_inventory,
-                &mut attacker_skill_set,
-                attacker_uid,
-                &mut outcomes,
-            );
-        }
+            }
+        }).flatten().for_each(|(attacker, exp_reward)| {
+            // Process the calculated EXP rewards
+            if let (Some(mut attacker_skill_set), Some(attacker_uid), Some(attacker_inventory)) = (
+                skill_sets.get_mut(attacker),
+                uids.get(attacker),
+                inventories.get(attacker),
+            ) {
+                handle_exp_gain(
+                    exp_reward,
+                    attacker_inventory,
+                    &mut attacker_skill_set,
+                    attacker_uid,
+                    &mut outcomes,
+                );
+            }
+        });
     })();
 
     let should_delete = if state
@@ -458,7 +523,9 @@ pub fn handle_land_on_ground(server: &Server, entity: EcsEntity, vel: Vec3<f32>)
                 stats.get(entity),
                 Some(DamageKind::Crushing),
             );
-            let change = damage.calculate_health_change(damage_reduction, None, false, 0.0, 1.0);
+            let time = server.state.ecs().read_resource::<Time>();
+            let change =
+                damage.calculate_health_change(damage_reduction, None, false, 0.0, 1.0, *time);
             health.change_by(change);
         }
         // Handle poise change
@@ -774,6 +841,7 @@ pub fn handle_explosion(server: &Server, pos: Vec3<f32>, explosion: Explosion, o
                                 .map(|(entity, uid)| combat::AttackerInfo {
                                     entity,
                                     uid,
+                                    group: groups.get(entity),
                                     energy: energies.get(entity),
                                     combo: combos.get(entity),
                                     inventory: inventories.get(entity),
@@ -806,6 +874,7 @@ pub fn handle_explosion(server: &Server, pos: Vec3<f32>, explosion: Explosion, o
                             target_group,
                         };
 
+                        let time = server.state.ecs().read_resource::<Time>();
                         attack.apply_attack(
                             attacker_info,
                             target_info,
@@ -813,6 +882,7 @@ pub fn handle_explosion(server: &Server, pos: Vec3<f32>, explosion: Explosion, o
                             attack_options,
                             strength,
                             combat::AttackSource::Explosion,
+                            *time,
                             |e| emitter.emit(e),
                             |o| outcomes.push(o),
                         );
diff --git a/server/src/state_ext.rs b/server/src/state_ext.rs
index 9ae8599926..138ab86323 100644
--- a/server/src/state_ext.rs
+++ b/server/src/state_ext.rs
@@ -10,13 +10,14 @@ use crate::{
 use common::{
     character::CharacterId,
     combat,
+    combat::DamageContributor,
     comp::{
         self,
         skills::{GeneralSkill, Skill},
         Group, Inventory, Poise,
     },
     effect::Effect,
-    resources::TimeOfDay,
+    resources::{Time, TimeOfDay},
     slowjob::SlowJobPool,
     uid::{Uid, UidAllocator},
 };
@@ -127,16 +128,27 @@ impl StateExt for State {
             Effect::Damage(damage) => {
                 let inventories = self.ecs().read_storage::<Inventory>();
                 let stats = self.ecs().read_storage::<comp::Stats>();
+                let groups = self.ecs().read_storage::<comp::Group>();
+
+                let damage_contributor = source
+                    .map(|uid| {
+                        self.ecs().entity_from_uid(uid.0).map(|attacker_entity| {
+                            DamageContributor::new(uid, groups.get(attacker_entity).cloned())
+                        })
+                    })
+                    .flatten();
+                let time = self.ecs().read_resource::<Time>();
                 let change = damage.calculate_health_change(
                     combat::Damage::compute_damage_reduction(
                         inventories.get(entity),
                         stats.get(entity),
                         Some(damage.kind),
                     ),
-                    source,
+                    damage_contributor,
                     false,
                     0.0,
                     1.0,
+                    *time,
                 );
                 self.ecs()
                     .write_storage::<comp::Health>()
diff --git a/server/src/sys/agent.rs b/server/src/sys/agent.rs
index 0c192751be..d72c34d17b 100644
--- a/server/src/sys/agent.rs
+++ b/server/src/sys/agent.rs
@@ -473,10 +473,13 @@ impl<'a> System<'a> for Sys {
                         // Target an entity that's attacking us if the attack
                         // was recent and we have a health component
                         match health {
-                            Some(health) if health.last_change.0 < DAMAGE_MEMORY_DURATION => {
-                                if let Some(by) = health.last_change.1.damage_by() {
+                            Some(health)
+                                if read_data.time.0 - health.last_change.time.0
+                                    < DAMAGE_MEMORY_DURATION =>
+                            {
+                                if let Some(by) = health.last_change.damage_by() {
                                     if let Some(attacker) =
-                                        read_data.uid_allocator.retrieve_entity_internal(by.id())
+                                        read_data.uid_allocator.retrieve_entity_internal(by.uid().0)
                                     {
                                         // If the target is dead or in a safezone, remove the
                                         // target and idle.
@@ -550,7 +553,7 @@ impl<'a> System<'a> for Sys {
                                         }
                                     }
                                 }
-                            },
+                            }
                             _ => {},
                         }
 
@@ -1581,17 +1584,19 @@ impl<'a> AgentData<'a> {
         let guard_duty = |e_health: &Health, e_alignment: Option<&Alignment>| {
             // I'm a guard and a villager is in distress
             let other_is_npc = matches!(e_alignment, Some(Alignment::Npc));
-            let remembers_damage = e_health.last_change.0 < 5.0;
+            let remembers_damage = read_data.time.0 - e_health.last_change.time.0 < 5.0;
             let need_help = read_data.stats.get(*self.entity).map_or(false, |stats| {
                 stats.name == "Guard" && other_is_npc && remembers_damage
             });
 
-            let attacker_of = |health: &Health| health.last_change.1.damage_by();
+            let attacker_of = |health: &Health| health.last_change.damage_by();
 
             need_help
                 .then(|| {
                     attacker_of(e_health)
-                        .and_then(|attacker_uid| get_entity_by_id(attacker_uid.id(), read_data))
+                        .and_then(|damage_contributor| {
+                            get_entity_by_id(damage_contributor.uid().0, read_data)
+                        })
                         .and_then(|attacker| {
                             read_data
                                 .positions
@@ -4217,8 +4222,8 @@ impl<'a> AgentData<'a> {
     ) {
         if let Some(Target { target, .. }) = agent.target {
             if let Some(tgt_health) = read_data.healths.get(target) {
-                if let Some(by) = tgt_health.last_change.1.damage_by() {
-                    if let Some(attacker) = get_entity_by_id(by.id(), read_data) {
+                if let Some(by) = tgt_health.last_change.damage_by() {
+                    if let Some(attacker) = get_entity_by_id(by.uid().0, read_data) {
                         if agent.target.is_none() {
                             controller.push_event(ControlEvent::Utterance(UtteranceKind::Angry));
                         }
@@ -4483,7 +4488,8 @@ fn decrement_awareness(agent: &mut Agent) {
 
 fn entity_was_attacked(entity: EcsEntity, read_data: &ReadData) -> bool {
     if let Some(entity_health) = read_data.healths.get(entity) {
-        entity_health.last_change.0 < 5.0 && entity_health.last_change.1.amount < 0.0
+        read_data.time.0 - entity_health.last_change.time.0 < 5.0
+            && entity_health.last_change.amount < 0.0
     } else {
         false
     }
diff --git a/voxygen/src/audio/music.rs b/voxygen/src/audio/music.rs
index b31fd50f98..573310a983 100644
--- a/voxygen/src/audio/music.rs
+++ b/voxygen/src/audio/music.rs
@@ -54,7 +54,7 @@ use hashbrown::HashMap;
 use rand::{prelude::SliceRandom, thread_rng, Rng};
 use serde::Deserialize;
 use std::time::Instant;
-use tracing::{debug, warn};
+use tracing::{debug, trace, warn};
 
 /// Collection of all the tracks
 #[derive(Debug, Deserialize)]
@@ -289,9 +289,10 @@ impl MusicMgr {
             if interrupt {
                 self.last_interrupt = Instant::now();
             }
-            debug!(
+            trace!(
                 "pre-play_random_track: {:?} {:?}",
-                self.last_activity, music_state
+                self.last_activity,
+                music_state
             );
             if let Ok(next_activity) = self.play_random_track(audio, state, client, &music_state) {
                 self.last_activity = next_activity;
diff --git a/voxygen/src/ecs/sys/floater.rs b/voxygen/src/ecs/sys/floater.rs
index 0f67af2ea4..5fbcf4786e 100644
--- a/voxygen/src/ecs/sys/floater.rs
+++ b/voxygen/src/ecs/sys/floater.rs
@@ -71,7 +71,7 @@ impl<'a> System<'a> for Sys {
                 // would just be a transient glitch in the display of these damage numbers)
                 // (maybe health changes could be sent to the client as a list
                 // of events)
-                if match health.last_change.1.by {
+                if match health.last_change.by.map(|x| x.uid()) {
                     // HealthSource::Damage { by: Some(by), .. }
                     // | HealthSource::Heal { by: Some(by) } => {
                     //     let by_me = my_uid.map_or(false, |&uid| by == uid);
@@ -101,12 +101,12 @@ impl<'a> System<'a> for Sys {
                     match last_floater {
                         Some(f) if f.timer < HP_ACCUMULATETIME => {
                             //TODO: Add "jumping" animation on floater when it changes its value
-                            f.hp_change += health.last_change.1.amount;
+                            f.hp_change += health.last_change.amount;
                         },
                         _ => {
                             hp_floater_list.floaters.push(HpFloater {
                                 timer: 0.0,
-                                hp_change: health.last_change.1.amount,
+                                hp_change: health.last_change.amount,
                                 rand: rand::random(),
                             });
                         },
diff --git a/voxygen/src/scene/figure/mod.rs b/voxygen/src/scene/figure/mod.rs
index cb27054041..bdc9c9ee8e 100644
--- a/voxygen/src/scene/figure/mod.rs
+++ b/voxygen/src/scene/figure/mod.rs
@@ -35,7 +35,7 @@ use common::{
         Body, CharacterState, Collider, Controller, Health, Inventory, Item, Last, LightAnimation,
         LightEmitter, Mounting, Ori, PhysicsState, PoiseState, Pos, Scale, Vel,
     },
-    resources::DeltaTime,
+    resources::{DeltaTime, Time},
     states::{equipping, idle, utils::StageSection, wielding},
     terrain::TerrainChunk,
     uid::UidAllocator,
@@ -752,9 +752,11 @@ impl FigureMgr {
             // Change in health as color!
             let col = health
                 .map(|h| {
+                    let time = scene_data.state.ecs().read_resource::<Time>();
+                    let time_since_health_change = time.0 - h.last_change.time.0;
                     vek::Rgba::broadcast(1.0)
                         + vek::Rgba::new(10.0, 10.0, 10.0, 0.0).map(|c| {
-                            (c / (1.0 + DAMAGE_FADE_COEFFICIENT * h.last_change.0)) as f32
+                            (c / (1.0 + DAMAGE_FADE_COEFFICIENT * time_since_health_change)) as f32
                         })
                 })
                 .unwrap_or_else(|| vek::Rgba::broadcast(1.0))