Cheapest priced copy (Stronghold): $0.35 at Card Kingdom, near mint, their price list as of .
Mask of the Mimic 
Instant · Uncommon · Stronghold · #37
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, put that card onto the battlefield, then shuffle.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
1 printing · $0.35 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Stronghold | 37 | Uncommon | $0.35 | — |
5 rulings from Wizards of the Coast
- 4 October 2004If 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 October 2004You look for a card of the same name, the current type of the card does not matter.
- 4 October 2004You do not have to find a card if you do not want to.
- 15 April 2013Players 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.
- 15 April 2013You must sacrifice exactly one creature to cast this spell; you cannot cast it without sacrificing a creature, and you cannot sacrifice additional creatures.