2 Level 8 monsters
Must first be either: Xyz Summoned or Ritual Summoned by "Animagus Dark Arts" OR: Using 1 Rank 4 or lower Beast-Mage-Type Xyz Monster you control as the Xyz Material. (This is treated as an Xyz Summon. Xyz Materials attached to that monster also become Xyz Materials on this card.) If this card battles an opponent's monster, that monster's ATK becomes 0 until the end of the Damage Step. Once per turn, during either player's Battle Phase, if your opponent activates a card or effect: You can detach 1 Xyz Material from this card; negate the activation or effect, and if you do, shuffle that card into the Deck, then this card gains 500 ATK until the end of this turn.