Thassa, Deep-Dwelling is a mythic Legendary Enchantment Creature — God card from Theros Beyond Death Promos (PTHB), collector number 71p. Current market price: $28.85 (foil $39.84), TCGplayer market prices via Scryfall.
Indestructible As long as your devotion to blue is less than five, Thassa isn't a creature. At the beginning of your end step, exile up to one other target creature you control, then return that card to the battlefield under your control. {3}{U}: Tap another target creature.