Shriekmaw is a uncommon Creature — Elemental card from Murders at Karlov Manor Commander (MKC), collector number 139. Current market price: $0.27, TCGplayer market prices via Scryfall.
Fear (This creature can't be blocked except by artifact creatures and/or black creatures.) When this creature enters, destroy target nonartifact, nonblack creature. Evoke {1}{B} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)