Cabal Executioner is a uncommon Creature — Human Cleric card from Onslaught (ONS), collector number 130. Current market price: $0.18 (foil $1.45), TCGplayer market prices via Scryfall.
Whenever this creature deals combat damage to a player, that player sacrifices a creature of their choice. Morph {3}{B}{B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)