Mystic Subdual is a uncommon Enchantment — Aura card from Ikoria: Lair of Behemoths (IKO), collector number 57. Current market price: $0.22 (foil $0.30), TCGplayer market prices via Scryfall.
Flash Enchant creature Enchanted creature gets -2/-0 and loses all abilities. (Mutating onto the creature won't give it new abilities. It can gain abilities in other ways.)