[RD/VSP1] Radiant Mirror Force

Hrm a certain Deck can have 3 cards on the field and yet not be 3 monsters…

RD/VSP1-JP055 閃光のバリア －シャイニング・フォース－ Senkou no Barrier -Shining Force- (Barrier of Flashing Light -Shining Force-/Radiant Mirror Force)
Normal Trap Card
[REQUIREMENT] If your opponent controls 3 Attack Position monsters, when your opponent’s monster declares an attack, you can activate this.
[EFFECT] Destroy all Attack Position monsters your opponent controls.

Source