Abyss Dweller (DUDE-EN016) [Duel Devastator]

2 Level 4 monsters
<br>While this card has an Xyz Material attached that was originally WATER, all WATER monsters you control gain 500 ATK. Once per turn, during either player's turn: You can detach 1 Xyz Material from this card; any card effects that activate in your opponent's Graveyard cannot be activated this turn.