Number C73: Abyss Supra Splash

3 Level 6 monsters If a monster you control battles an opponent's monster, during damage calculation (in either player's turn): You can detach 1 Xyz Material from this card once per battle; your battling monster gains ATK equal to the ATK of the opponent's monster it is battling, during that damage calculation only. If this card has "Number 73: Abyss Splash" as Xyz Material, it gains this effect. ? This card cannot be destroyed by card effects.