Helm of Obedience - Alliances (ALL)

X, T: Put the top card of target opponent's library into his or her graveyard. Continue doing this until you have put X cards or a creature card into that graveyard, whichever occurs first. If the last card put into the graveyard is a creature card, bury Helm of Obedience and put that creature into play under your control as though it were just cast. X cannot be equal to 0.