Mystic Subdual is a uncommon Enchantment — Aura card from The List (PLST), collector number IKO-57. Current market price: $0.09, 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.)