Mistform Warchief is a uncommon Creature — Illusion card from Scourge (SCG), collector number 43. Current market price: $0.21 (foil $2.55), TCGplayer market prices via Scryfall.
Creature spells you cast that share a creature type with this creature cost {1} less to cast. {T}: This creature becomes the creature type of your choice until end of turn.