Once per turn: You can Tribute 1 or more Vendread monsters from your hand and or field, then target 1 face-up monster you control; increase its Level by the number of monsters Tributed, until the end of this turn. When your attacking Vendread Ritual Monster destroys an opponent s monster by battle: You can have your monster gain 1000 ATK. You can only use this effect of Vendread Nightmare once per turn.