2 Level 8 DARK monsters Must be Xyz Summoned and cannot be Special Summoned by other ways. Once per turn, during either player's turn: You can detach 1 Xyz Material from this card and send 1 card from your hand to the Graveyard to target 1 face-up card your opponent controls; change this card to Defense Position, and if you do, negate that face-up card's effect until the End Phase.