Emperor Mihail II is a rare Legendary Creature — Merfolk Noble card from Dominaria United Commander (DMC), collector number 23. Current market price: $0.46 (foil $0.92), TCGplayer market prices via Scryfall.
You may look at the top card of your library any time. You may cast Merfolk spells from the top of your library. Whenever you cast a Merfolk spell, you may pay {1}. If you do, create a 1/1 blue Merfolk creature token.