Diviner of Mist is a rare Creature — Dragon card from Tarkir: Dragonstorm Commander (TDC), collector number 20. Current market price: $0.23, TCGplayer market prices via Scryfall.
Flying Whenever this creature attacks, mill four cards. You may cast an instant or sorcery spell from your graveyard with mana value 4 or less without paying its mana cost. If that spell would be put into your graveyard, exile it instead.