Proteus Machine is a uncommon Artifact Creature — Shapeshifter card from Scourge (SCG), collector number 141. Current market price: $0.25 (foil $3.76), TCGplayer market prices via Scryfall.
Morph {0} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.) When this creature is turned face up, it becomes the creature type of your choice. (This effect lasts indefinitely.)