Headhunter is a uncommon Creature — Human Cleric card from Onslaught (ONS), collector number 156. Current market price: $0.30 (foil $6.10), TCGplayer market prices via Scryfall.
Whenever this creature deals combat damage to a player, that player discards a card. Morph {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.)