Emperor Mihail II is a rare Legendary Creature — Merfolk Noble card from The Lost Caverns of Ixalan Commander (LCC), collector number 155. Current market price: $0.35, 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.