Crystal Keeper

[ Pendulum Effect ] Each turn, the first time an "Ultimate Crystal" monster(s) and/or "Crystal Beast" card(s) you control would be destroyed by card effect that turn, it is not destroyed. [ Monster Effect ] If a "Crystal Beast" monster you control battles an opponent's monster, during damage calculation (Quick Effect): You can Tribute this card from your hand or face-up field; your battling monster's ATK/DEF become double its original ATK/DEF during that damage calculation only, but it is destroyed at the end of this Damage Step.

Pendulum Effect (Scale 2)
Each turn, the first time an "Ultimate Crystal" monster(s) and/or "Crystal Beast" card(s) you control would be destroyed by card effect that turn, it is not destroyed.