diff --git a/test/moves/first-attack-double-power.test.ts b/test/moves/first-attack-double-power.test.ts
new file mode 100644
index 00000000000..d297f60d052
--- /dev/null
+++ b/test/moves/first-attack-double-power.test.ts
@@ -0,0 +1,96 @@
+import { BattlerIndex } from "#app/battle";
+import { allMoves } from "#app/data/moves/move";
+import { Abilities } from "#enums/abilities";
+import { BattleType } from "#enums/battle-type";
+import { Moves } from "#enums/moves";
+import { Species } from "#enums/species";
+import GameManager from "#test/testUtils/gameManager";
+import Phaser from "phaser";
+import { afterEach, beforeAll, beforeEach, describe, expect, it, vi, type MockInstance } from "vitest";
+
+describe.each<{ name: string; move: Moves }>([
+  { name: "Fishious Rend", move: Moves.FISHIOUS_REND },
+  { name: "Bolt Beak", move: Moves.BOLT_BEAK },
+])("Moves - $name", ({ move }) => {
+  let phaserGame: Phaser.Game;
+  let game: GameManager;
+  let powerSpy: MockInstance;
+
+  beforeAll(() => {
+    phaserGame = new Phaser.Game({
+      type: Phaser.HEADLESS,
+    });
+  });
+
+  afterEach(() => {
+    game.phaseInterceptor.restoreOg();
+  });
+
+  beforeEach(() => {
+    game = new GameManager(phaserGame);
+    game.override
+      .moveset(move)
+      .ability(Abilities.BALL_FETCH)
+      .battleStyle("single")
+      .battleType(BattleType.TRAINER)
+      .disableCrits()
+      .enemyLevel(100)
+      .enemySpecies(Species.MAGIKARP)
+      .enemyAbility(Abilities.BALL_FETCH)
+      .enemyMoveset(Moves.SPLASH);
+
+    powerSpy = vi.spyOn(allMoves[move], "calculateBattlePower");
+  });
+
+  it("should double power when the user moves after the target", async () => {
+    await game.classicMode.startBattle([Species.FEEBAS]);
+
+    // turn 1: enemy, then player (no boost)
+    game.move.select(move);
+    await game.setTurnOrder([BattlerIndex.ENEMY, BattlerIndex.PLAYER]);
+    await game.toNextTurn();
+
+    expect(powerSpy).toHaveLastReturnedWith(allMoves[move].power);
+
+    // turn 2: player, then enemy (boost)
+    game.move.select(move);
+    await game.setTurnOrder([BattlerIndex.ENEMY, BattlerIndex.PLAYER]);
+    await game.toNextTurn();
+
+    expect(powerSpy).toHaveLastReturnedWith(allMoves[move].power * 2);
+  });
+
+  it("should double power on the turn the target switches in", async () => {
+    await game.classicMode.startBattle([Species.FEEBAS]);
+
+    game.move.select(move);
+    game.forceEnemyToSwitch();
+    await game.toNextTurn();
+
+    expect(powerSpy).toHaveLastReturnedWith(allMoves[move].power * 2);
+  });
+
+  // TODO: Verify behavior with Instruct/Dancer
+  it.todo.each<{ type: string; allyMove: Moves }>([
+    { type: "a Dancer-induced", allyMove: Moves.FIERY_DANCE },
+    { type: "an Instructed", allyMove: Moves.INSTRUCT },
+  ])("should double power if $type move is used as the target's first action", async ({ allyMove }) => {
+    game.override.battleStyle("double").moveset([move, allyMove]).ability(Abilities.DANCER);
+    await game.classicMode.startBattle([Species.DRACOVISH, Species.ARCTOZOLT]);
+
+    // Simulate enemy having used splash last turn to allow Instruct to copy it
+    const enemy = game.scene.getEnemyPokemon()!;
+    enemy.pushMoveHistory({
+      move: Moves.SPLASH,
+      targets: [BattlerIndex.ENEMY],
+      turn: game.scene.currentBattle.turn - 1,
+    });
+
+    game.move.select(move, BattlerIndex.PLAYER, BattlerIndex.ENEMY);
+    game.move.select(allyMove, BattlerIndex.PLAYER_2, BattlerIndex.ENEMY);
+    await game.setTurnOrder([BattlerIndex.PLAYER_2, BattlerIndex.PLAYER, BattlerIndex.ENEMY, BattlerIndex.ENEMY_2]);
+    await game.toNextTurn();
+
+    expect(powerSpy).toHaveLastReturnedWith(allMoves[move].power);
+  });
+});