[Ability] fix damage taken by disguise (#2601)

src/data/ability.ts

@@ -333,7 +333,7 @@ export class PreDefendMoveDamageToOneAbAttr extends ReceivedMoveDamageMultiplier
 
   applyPreDefend(pokemon: Pokemon, passive: boolean, attacker: Pokemon, move: Move, cancelled: Utils.BooleanHolder, args: any[]): boolean {
     if (this.condition(pokemon, attacker, move)) {
-      (args[0] as Utils.NumberHolder).value = 1;
+      (args[0] as Utils.NumberHolder).value = Math.floor(pokemon.getMaxHp() / 8);
       return true;
     }
 

src/test/abilities/disguise.test.ts

@@ -64,4 +64,35 @@ describe("Abilities - DISGUISE", () => {
     },
     TIMEOUT
   );
+
+  test(
+    "damage taken should be equal to 1/8 of its maximum HP, rounded down",
+    async () => {
+      const baseForm = 0,
+        bustedForm = 1;
+
+      vi.spyOn(Overrides, "OPP_MOVESET_OVERRIDE", "get").mockReturnValue([Moves.DARK_PULSE, Moves.DARK_PULSE, Moves.DARK_PULSE, Moves.DARK_PULSE]);
+      vi.spyOn(Overrides, "STARTING_LEVEL_OVERRIDE", "get").mockReturnValue(20);
+      vi.spyOn(Overrides, "OPP_LEVEL_OVERRIDE", "get").mockReturnValue(20);
+      vi.spyOn(Overrides, "OPP_SPECIES_OVERRIDE", "get").mockReturnValue(Species.MAGIKARP);
+      vi.spyOn(Overrides, "STARTER_FORM_OVERRIDES", "get").mockReturnValue({
+        [Species.MIMIKYU]: baseForm,
+      });
+
+      await game.startBattle([Species.MIMIKYU]);
+
+      const mimikyu = game.scene.getPlayerPokemon();
+      const damage = (Math.floor(mimikyu.getMaxHp()/8));
+
+      expect(mimikyu).not.toBe(undefined);
+      expect(mimikyu.formIndex).toBe(baseForm);
+
+      game.doAttack(getMovePosition(game.scene, 0, Moves.SPLASH));
+      await game.phaseInterceptor.to(TurnEndPhase);
+
+      expect(mimikyu.formIndex).toBe(bustedForm);
+      expect(game.scene.getEnemyPokemon().turnData.currDamageDealt).toBe(damage);
+    },
+    TIMEOUT
+  );
 });