Cage of Nightmares
■ [Set] ■ The abilities of this card on the field cannot be nullified. ■ When a «Black Dragon» monster enters your field, put the top card of your opponent's deck into his or her drop zone. This ability only activates once per turn. ■ When this card is put into the drop zone from the field, put up to one «Black Dragon» monster from your drop zone into your hand.