Moonshaker Cavalry is a mythic Creature — Spirit Knight card from Wilds of Eldraine Promos (PWOE), collector number 21p. Current market price: $10.08 (foil $10.53), TCGplayer market prices via Scryfall.
Flying When this creature enters, creatures you control gain flying and get +X/+X until end of turn, where X is the number of creatures you control.