Spadassin Mystique LV6 RDS-FR008

If you Summon this card by Normal Summon, you must place it in Defense Position face-down. If this card attacks an opponent's monster in face-down Defense Position, destroy that monster immediately with this card's effect without flipping it face-up or calculating damage. You can return the destroyed monster to the top of your opponent's Deck instead of sending it to the Graveyard due to this effect.