Possessed Goat 
Creature — Goat
, Discard a card: Put three +1/+1 counters on this creature and it becomes a black Demon in addition to its other colors and types. Activate only once.
Legality
standardLEGALpioneerLEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL