The Ultimate Creature of Destruction (Purple)

Target 1 “Blue-Eyes” monster you control; this turn, that face-up monster is unaffected by card effects, except its own, it cannot be destroyed by battle, also any opponent’s monster it battles is destroyed at the end of the Damage Step. While this card is in your GY, if you Normal or Special Summon a “Blue-Eyes White Dragon”: You can Set this card, but banish it when it leaves the field. You can only use this effect of “The Ultimate Creature of Destruction” once per turn.