Morpheus, the Dream Mirror White Knight

If this card is Special Summoned by the effect of a "Dream Mirror" monster: You can activate this effect; this card cannot be destroyed by battle or card effects this turn. During the Main or Battle Phase, if "Dream Mirror of Terror" is in a Field Zone (Quick Effect): You can Tribute this card; Special Summon 1 "Morpheus, the Dream Mirror Black Knight" from your Deck. You can only use each effect of "Morpheus, the Dream Mirror White Knight" once per turn.