Narset, Enlightened Master is a mythic Legendary Creature — Human Monk card from Khans of Tarkir (KTK), collector number 190. Current market price: $0.42 (foil $4.16), TCGplayer market prices via Scryfall.
First strike, hexproof Whenever Narset attacks, exile the top four cards of your library. Until end of turn, you may cast noncreature spells from among those cards without paying their mana costs.