Protean Thaumaturge is a rare Creature — Human Wizard card from Theros Beyond Death Promos (PTHB), collector number 60p. Current market price: $0.44 (foil $1.39), TCGplayer market prices via Scryfall.
Constellation — Whenever an enchantment you control enters, you may have this creature become a copy of another target creature, except it has this ability.