Mask of the Mimic

Oracle Text

As an additional cost to cast this spell, sacrifice a creature.

Search your library for a card with the same name as target nontoken creature and put that card onto the battlefield. Then shuffle your library.

Card Rulings

10/4/2004 You look for a card of the same name, the current type of the card does not matter.
10/4/2004 You do not have to find a card if you do not want to.
10/4/2004 If a copy card is targeted by this effect, you get to look for another copy of the card it is copying. This is because a copy card actually takes on the name and initial characteristics of what it copies.
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.