diff --git a/src/battle-phases.ts b/src/battle-phases.ts
index 486ad7ba4..c62d6cf12 100644
--- a/src/battle-phases.ts
+++ b/src/battle-phases.ts
@@ -1982,11 +1982,25 @@ export class DamagePhase extends PokemonPhase {
   start() {
     super.start();
 
+    if (this.damageResult === HitResult.ONE_HIT_KO) {
+      this.scene.toggleInvert(true);
+      this.scene.time.delayedCall(Utils.fixedInt(1000), () => {
+        this.scene.toggleInvert(false);
+        this.applyDamage();
+      });
+      return;
+    }
+
+    this.applyDamage();
+  }
+
+  applyDamage() {
     switch (this.damageResult) {
       case HitResult.EFFECTIVE:
         this.scene.playSound('hit');
         break;
       case HitResult.SUPER_EFFECTIVE:
+      case HitResult.ONE_HIT_KO:
         this.scene.playSound('hit_strong');
         break;
       case HitResult.NOT_VERY_EFFECTIVE:
diff --git a/src/battle-scene.ts b/src/battle-scene.ts
index e3ce16b3a..cc1e62446 100644
--- a/src/battle-scene.ts
+++ b/src/battle-scene.ts
@@ -33,6 +33,7 @@ import { Setting, settingOptions } from './system/settings';
 import SettingsUiHandler from './ui/settings-ui-handler';
 import MessageUiHandler from './ui/message-ui-handler';
 import { Species } from './data/species';
+import InvertPostFX from './pipelines/invert';
 
 const enableAuto = true;
 const quickStart = false;
@@ -1072,6 +1073,13 @@ export default class BattleScene extends Phaser.Scene {
 		return 0;
 	}
 
+	toggleInvert(invert: boolean): void {
+		if (invert)
+			this.cameras.main.setPostPipeline(InvertPostFX);
+		else
+			this.cameras.main.removePostPipeline('InvertPostFX');
+	}
+
 	getCurrentPhase(): BattlePhase {
 		return this.currentPhase;
 	}
diff --git a/src/data/move.ts b/src/data/move.ts
index ec0a41586..0ec2af072 100644
--- a/src/data/move.ts
+++ b/src/data/move.ts
@@ -1313,16 +1313,13 @@ export class ClearWeatherAttr extends MoveEffectAttr {
   }
 }
 
-export class OneHitKOAttr extends MoveEffectAttr {
-  constructor() {
-    super(false, MoveEffectTrigger.HIT);
-  }
-
+export class OneHitKOAttr extends MoveAttr {
   apply(user: Pokemon, target: Pokemon, move: Move, args: any[]): boolean {
     if (target.species.speciesId === Species.ETERNATUS && target.formIndex === 1)
       return false;
-    target.damage(target.hp, true);
-    user.scene.queueMessage('It\'s a one-hit KO!');
+
+    (args[0] as Utils.BooleanHolder).value = true;
+    
     return true;
   }
 }
diff --git a/src/main.ts b/src/main.ts
index f43b9e062..a9cbd3641 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -1,5 +1,6 @@
 import Phaser from 'phaser';
 import BattleScene from './battle-scene';
+import InvertPostFX from './pipelines/invert';
 
 const config: Phaser.Types.Core.GameConfig = {
 	type: Phaser.WEBGL,
@@ -10,6 +11,7 @@ const config: Phaser.Types.Core.GameConfig = {
 		mode: Phaser.Scale.FIT
 	},
 	pixelArt: true,
+	pipeline: [ InvertPostFX ] as unknown as Phaser.Types.Core.PipelineConfig,
 	scene: [ BattleScene ]
 };
 
diff --git a/src/pipelines/invert.ts b/src/pipelines/invert.ts
new file mode 100644
index 000000000..21a2a9439
--- /dev/null
+++ b/src/pipelines/invert.ts
@@ -0,0 +1,27 @@
+import { Game } from "phaser";
+
+const fragShader = `
+precision mediump float;
+
+uniform sampler2D uMainSampler;
+
+varying vec2 outTexCoord;
+
+void main()
+{
+    gl_FragColor = 1.0 - texture2D(uMainSampler, outTexCoord);
+}
+`;
+
+export default class InvertPostFX extends Phaser.Renderer.WebGL.Pipelines.PostFXPipeline {
+    constructor (game: Game) {
+        super({
+            game,
+            name: 'InvertPostFX',
+            fragShader,
+            uniforms: [
+                'uMainSampler'
+            ]
+        } as Phaser.Types.Renderer.WebGL.WebGLPipelineConfig);
+    }
+}
\ No newline at end of file
diff --git a/src/pokemon.ts b/src/pokemon.ts
index e315658a7..fc4559ba4 100644
--- a/src/pokemon.ts
+++ b/src/pokemon.ts
@@ -1,7 +1,7 @@
 import Phaser from 'phaser';
 import BattleScene, { AnySound } from './battle-scene';
 import BattleInfo, { PlayerBattleInfo, EnemyBattleInfo } from './ui/battle-info';
-import Move, { HighCritAttr, HitsTagAttr, applyMoveAttrs, FixedDamageAttr, VariablePowerAttr, Moves, allMoves, MoveCategory, TypelessAttr, CritOnlyAttr, getMoveTargets, AttackMove, AddBattlerTagAttr } from "./data/move";
+import Move, { HighCritAttr, HitsTagAttr, applyMoveAttrs, FixedDamageAttr, VariablePowerAttr, Moves, allMoves, MoveCategory, TypelessAttr, CritOnlyAttr, getMoveTargets, AttackMove, AddBattlerTagAttr, OneHitKOAttr } from "./data/move";
 import { default as PokemonSpecies, PokemonSpeciesForm, getPokemonSpecies } from './data/pokemon-species';
 import * as Utils from './utils';
 import { Type, TypeDamageMultiplier, getTypeDamageMultiplier } from './data/type';
@@ -790,14 +790,22 @@ export default abstract class Pokemon extends Phaser.GameObjects.Container {
           console.log('damage', damage, move.name, move.power, sourceAtk, targetDef);
           
           if (!result) {
-            if (typeMultiplier.value >= 2)
-              result = HitResult.SUPER_EFFECTIVE;
-            else if (typeMultiplier.value >= 1)
-              result = HitResult.EFFECTIVE;
-            else if (typeMultiplier.value > 0)
-              result = HitResult.NOT_VERY_EFFECTIVE;
-            else
+            if (!typeMultiplier.value)
               result = HitResult.NO_EFFECT;
+            else {
+              const oneHitKo = new Utils.BooleanHolder(false);
+              applyMoveAttrs(OneHitKOAttr, source, this, move, oneHitKo);
+              if (oneHitKo.value) {
+                result = HitResult.ONE_HIT_KO;
+                isCritical = false;
+                damage.value = this.hp;
+              } else if (typeMultiplier.value >= 2)
+                result = HitResult.SUPER_EFFECTIVE;
+              else if (typeMultiplier.value >= 1)
+                result = HitResult.EFFECTIVE;
+              else
+                result = HitResult.NOT_VERY_EFFECTIVE;
+            }
           }
 
           if (!source.isPlayer())
@@ -828,6 +836,9 @@ export default abstract class Pokemon extends Phaser.GameObjects.Container {
               case HitResult.NO_EFFECT:
                 this.scene.queueMessage(`It doesn\'t affect ${this.name}!`);
                 break;
+              case HitResult.ONE_HIT_KO:  
+                this.scene.queueMessage('It\'s a one-hit KO!');
+                break;
             }
           }
 
@@ -1692,13 +1703,14 @@ export enum HitResult {
   SUPER_EFFECTIVE,
   NOT_VERY_EFFECTIVE,
   NO_EFFECT,
+  ONE_HIT_KO,
   STATUS,
   FAIL,
   MISS,
   OTHER
 }
 
-export type DamageResult = HitResult.EFFECTIVE | HitResult.SUPER_EFFECTIVE | HitResult.NOT_VERY_EFFECTIVE | HitResult.OTHER;
+export type DamageResult = HitResult.EFFECTIVE | HitResult.SUPER_EFFECTIVE | HitResult.NOT_VERY_EFFECTIVE | HitResult.ONE_HIT_KO | HitResult.OTHER;
 
 export class PokemonMove {
   public moveId: Moves;