Greenbelt Radical is a uncommon Creature — Centaur Citizen card from Murders at Karlov Manor (MKM), collector number 163. Current market price: $0.28 (foil $0.13), TCGplayer market prices via Scryfall.
Disguise {5}{G}{G} (You may cast this card face down for {3} as a 2/2 creature with ward {2}. Turn it face up any time for its disguise cost.) When this creature is turned face up, put a +1/+1 counter on each creature you control. Creatures you control gain trample until end of turn.