diff --git a/common/damage/damaging.trait.js b/common/damage/damaging.trait.js
new file mode 100644
index 0000000..6991adc
--- /dev/null
+++ b/common/damage/damaging.trait.js
@@ -0,0 +1,65 @@
+import * as I from 'immutable';
+
+import {Trait} from '@avocado/entity';
+
+export class Damaging extends Trait {
+
+  static defaultParams() {
+    return {
+      affinities: [],
+      lock: 0.1,
+      power: 0,
+      variance: 0.2,
+    };
+  }
+
+  initialize() {
+    this._affinities = this.params.get('affinities').toJS();
+    this._collidingWith = [];
+    this._lock = this.params.get('lock');
+    this._power = this.params.get('power');
+    this._variance = this.params.get('variance');
+  }
+
+  get affinities() {
+    return this._affinities;
+  }
+
+  get lock() {
+    return this._lock;
+  }
+
+  get power() {
+    return this._power;
+  }
+
+  get variance() {
+    return this._variance;
+  }
+
+  listeners() {
+    return {
+
+      collisionEnd: (other) => {
+        const index = this._collidingWith.indexOf(other);
+        this._collidingWith.splice(index, 1);
+      },
+
+      collisionStart: (other) => {
+        this._collidingWith.push(other);
+      },
+
+    };
+  }
+
+  tick(elapsed) {
+    for (let i = 0; i < this._collidingWith.length; ++i) {
+      const entity = this._collidingWith[i];
+      if (entity.is('vulnerable')) {
+        entity.takeDamageFrom(this.entity);
+      }
+    }
+  }
+
+}
+
diff --git a/common/damage/emitter.js b/common/damage/emitter.js
new file mode 100644
index 0000000..b4efbe3
--- /dev/null
+++ b/common/damage/emitter.js
@@ -0,0 +1,71 @@
+import {Proton, TextNode, TextNodeRenderer} from '@avocado/graphics';
+
+export class DamageEmitter {
+
+  constructor() {
+    const proton = new Proton();
+    const emitter = new Proton.Emitter();
+    proton.addEmitter(emitter);
+    this.emitter = emitter;
+    this.proton = proton;
+  }
+
+  addRenderer(renderer) {
+    this.renderer = renderer;
+    this.proton.addRender(this.renderer);
+  }
+
+  emit(position, amount) {
+    // BUGS
+    const pz = new Proton.PointZone();
+    pz.x = position[0];
+    pz.y = -position[1];
+    const initializers = [
+      new Proton.Body(new DamageTextNode(Math.abs(amount))),
+      new Proton.Position(pz),
+      new Proton.Mass(1),
+      new Proton.Life(2),
+      new Proton.Velocity(
+        new Proton.Span(80, 120),
+        new Proton.Vector3D(0, 5, 0),
+        27.5
+      ),
+    ];
+    // Heh, bugs.
+    const rot = new Proton.Rotate(0, 0, 0);
+    rot.a = new Proton.Span(-.003, .003);
+    const behaviors = [
+      new Proton.Alpha(1, .5),
+      new Proton.Color(amount < 0 ? 0x00ff00 : 0xff0000),
+      new Proton.Scale(.6, 1),
+      new Proton.Force(0, -1, 0),
+      rot,
+    ];
+    this.emitter.createParticle(initializers, behaviors);
+  }
+
+  tick(elapsed) {
+    this.proton.tick(elapsed);
+  }
+
+}
+
+export class DamageTextNode extends TextNode {
+
+  constructor(damage) {
+    super(damage);
+    if (damage > 999) {
+      this.span.style.fontSize = '2em';
+    }
+    else if (damage > 99) {
+      this.span.style.fontSize = '1.5em';
+    }
+    else if (damage > 9) {
+      this.span.style.fontSize = '1.2em';
+    }
+    else {
+      this.span.style.fontSize = '1em';
+    }
+  }
+
+}
diff --git a/common/damage/vulnerable.trait.js b/common/damage/vulnerable.trait.js
new file mode 100644
index 0000000..567f0a2
--- /dev/null
+++ b/common/damage/vulnerable.trait.js
@@ -0,0 +1,108 @@
+import * as I from 'immutable';
+
+import {Trait} from '@avocado/entity';
+import {hasGraphics, TextNodeRenderer} from '@avocado/graphics';
+
+import {DamageEmitter} from './emitter';
+
+export class Vulnerable extends Trait {
+
+  static defaultState() {
+    return {
+      damageList: I.Map(),
+    };
+  }
+
+  initialize() {
+    this.damageList = {};
+    this.locks = new Map();
+    if (hasGraphics) {
+      this.emitter = new DamageEmitter();
+      this.setRenderer();
+    }
+  }
+
+  patchStateStep(key, step) {
+    if ('state' !== key) {
+      return;
+    }
+    const stateKey = step.path.substr(1);
+    const value = this.transformPatchValue(stateKey, step.value);
+    const stateKeyParts = stateKey.split('/');
+    switch (stateKeyParts[0]) {
+      case 'damageList':
+        for (let i = 0; i < value.length; ++i) {
+          const amount = value[i];
+          this.emitter.emit(this.entity.position, amount);
+        }
+        break;
+      default:
+        super.patchStateStep(key, step);
+        break;
+    }
+  }
+
+  setRenderer() {
+    if (this.entity.is('staged') && this.entity.stage) {
+      const renderer = new TextNodeRenderer('.damage', this.entity.stage);
+      this.emitter.addRenderer(renderer);
+    }
+  }
+
+  listeners() {
+    return {
+
+      stageChanged: () => {
+        this.setRenderer();
+      },
+
+    };
+  }
+
+  methods() {
+    return {
+
+      takeDamageFrom: (entity) => {
+        if (this.locks.has(entity)) {
+          return;
+        }
+        this.locks.set(entity, entity.lock);
+        const variance = Math.random() * entity.variance * 2 - entity.variance;
+        const difference = entity.power * variance;
+        const amount = (entity.power + difference) >> 0;
+        if (!this.damageList[entity.instanceUuid]) {
+          this.damageList[entity.instanceUuid] = [];
+        }
+        this.damageList[entity.instanceUuid].push(amount);
+      },
+
+    };
+  }
+
+  tick(elapsed) {
+    if (this.state.get('damageList').size > 0) {
+      this.state = this.state.set('damageList', I.Map());
+    }
+    if (Object.keys(this.damageList).length > 0) {
+      this.state = this.state.set('damageList', I.Map(this.damageList));
+      this.isDirty = true;
+      this.damageList = {};
+    }
+    if (hasGraphics) {
+      this.emitter.tick(elapsed);
+    }
+    const keys = Array.from(this.locks.keys());
+    for (let i = 0; i < keys.length; ++i) {
+      const key = keys[i];
+      const remaining = this.locks.get(key) - elapsed;
+      if (remaining <= 0) {
+        this.locks.delete(key);
+      }
+      else {
+        this.locks.set(key, remaining);
+      }
+    }
+  }
+
+}
+
diff --git a/resource/fire.png b/resource/fire.png
new file mode 100644
index 0000000..fa12008
Binary files /dev/null and b/resource/fire.png differ
diff --git a/server/create-entity-for-connection.js b/server/create-entity-for-connection.js
index 1ad2bf4..d9878f7 100644
--- a/server/create-entity-for-connection.js
+++ b/server/create-entity-for-connection.js
@@ -47,6 +47,7 @@ export function createEntityForConnection(socket) {
           },
         },
       },
+      vulnerable: {},
     },
   });
   entity.addTrait('controllable');
diff --git a/server/create-server-room.js b/server/create-server-room.js
index 062c8a0..8dc5b6b 100644
--- a/server/create-server-room.js
+++ b/server/create-server-room.js
@@ -1,5 +1,52 @@
 import {World} from '@avocado/physics/matter/world';
 import {Room} from '@avocado/topdown';
+// A fire.
+function fireJSON(position) {
+  return {
+    traits: {
+      collider: {
+        params: {
+          isSensor: true,
+        },
+      },
+      damaging: {
+        params: {
+          power: 70,
+          affinities: ['fire'],
+        },
+      },
+      existent: {},
+      visible: {},
+      physical: {},
+      pictured: {
+        params: {
+          images: {
+            initial: {
+              offset: [0, 0],
+              size: [16, 16], // Derive?
+              uri: '/fire.png',
+            },
+          }
+        },
+      },
+      positioned: {
+        state: {
+          x: position[0],
+          y: position[1],
+        },
+      },
+      shaped: {
+        params: {
+          shape: {
+            type: 'rectangle',
+            position: [0, 0],
+            size: [16, 16],
+          },
+        },
+      },
+    },
+  };
+}
 // A flower barrel.
 function flowerBarrelJSON(position) {
   return {
@@ -201,6 +248,7 @@ function kittyJSON(position) {
           },
         },
       },
+      vulnerable: {},
     },
   };
 }
@@ -243,6 +291,7 @@ const roomJSON = {
     },
   },
 };
+roomJSON.layers.everything.entities.push(fireJSON([200, 200]));
 for (let i = 0; i < 4; ++i) {
   const x = Math.floor(Math.random() * 284) + 50;
   const y = Math.floor(Math.random() * 284) + 50;
diff --git a/yarn.lock b/yarn.lock
index d075198..b78496c 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -37,8 +37,8 @@
     lodash.without "4.4.0"
 
 "@avocado/graphics@1.x":
-  version "1.0.1"
-  resolved "https://npm.i12e.cha0s.io/@avocado%2fgraphics/-/graphics-1.0.1.tgz#ce799e134425d9c5d117aafafd35d5f52d2defda"
+  version "1.0.2"
+  resolved "https://npm.i12e.cha0s.io/@avocado%2fgraphics/-/graphics-1.0.2.tgz#a424f69b0f0c12476ff58229e92c5f6dabc15506"
   dependencies:
     "@avocado/core" "1.x"
     "@avocado/math" "1.x"
@@ -47,6 +47,8 @@
     debug "^3.1.0"
     immutable "4.0.0-rc.12"
     pixi.js "4.8.6"
+    three "0.103.0"
+    three.proton.js "0.1.5"
 
 "@avocado/input@1.x":
   version "1.0.1"
@@ -3889,8 +3891,8 @@ resolve@^1.3.2:
     path-parse "^1.0.6"
 
 resource-loader@^2.2.3:
-  version "2.2.3"
-  resolved "https://npm.i12e.cha0s.io/resource-loader/-/resource-loader-2.2.3.tgz#2c8b075b7b9328a2e72fba6f51b4dff274870000"
+  version "2.2.4"
+  resolved "https://npm.i12e.cha0s.io/resource-loader/-/resource-loader-2.2.4.tgz#9bf43dba59475d56be29c796399211ce0e96fd2d"
   dependencies:
     mini-signals "^1.1.1"
     parse-uri "^1.0.0"
@@ -4367,6 +4369,14 @@ terser@^3.16.1:
     source-map "~0.6.1"
     source-map-support "~0.5.10"
 
+three.proton.js@0.1.5:
+  version "0.1.5"
+  resolved "https://npm.i12e.cha0s.io/three.proton.js/-/three.proton.js-0.1.5.tgz#3ae32fd9cf3b5698e3b546946e53badbda04948e"
+
+three@0.103.0:
+  version "0.103.0"
+  resolved "https://npm.i12e.cha0s.io/three/-/three-0.103.0.tgz#63b3dbccc861caad93269618061a73dadebae71b"
+
 through2@^2.0.0:
   version "2.0.5"
   resolved "https://npm.i12e.cha0s.io/through2/-/through2-2.0.5.tgz#01c1e39eb31d07cb7d03a96a70823260b23132cd"