Swords of Revealing Light (EGS1-EN021) [Egyptian God Deck: Slifer the Sky Dragon]

After this card's activation, it remains on the field, but you must destroy it during the End Phase of your opponent's 3rd turn. When this card is activated: If your opponent controls a face-down monster, flip all monsters they control face-up. While this card is face-up on the field, your opponent's monsters cannot declare an attack.