Altar of Bone
As an additional cost to cast this spell, sacrifice a creature.
Search your library for a creature card, reveal that card, and put it into your hand. Then shuffle your library.
10/4/2004 Because the “search” requires you to find a card with certain characteristics, you don’t have to find the card if you don’t want to.
4/15/2013 You must sacrifice exactly one creature to cast this spell; you cannot cast it without sacrificing a creature, and you cannot sacrifice additional creatures.
4/15/2013 Players can only respond once this spell has been cast and all its costs have been paid. No one can try to destroy the creature you sacrificed to prevent you from casting this spell.