Haunted Cadaver is a common Creature — Zombie card from Onslaught (ONS), collector number 154. Current market price: $0.15 (foil $0.53), TCGplayer market prices via Scryfall.
Whenever this creature deals combat damage to a player, you may sacrifice it. If you do, that player discards three cards. Morph {1}{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.)