Niv-Mizzet, Visionary is a mythic Legendary Creature — Dragon Wizard card from Foundations Promos (PFDN), collector number 123p. Current market price: $6.47 (foil $8.43), TCGplayer market prices via Scryfall.
Flying You have no maximum hand size. Whenever a source you control deals noncombat damage to an opponent, you draw that many cards.