Niv-Mizzet Reborn is a mythic Legendary Creature — Dragon Avatar card from War of the Spark Promos (PWAR), collector number 208s. Current market price: — (foil $4.50), TCGplayer market prices via Scryfall.
Flying When Niv-Mizzet enters, reveal the top ten cards of your library. For each color pair, choose a card that's exactly those colors from among them. Put the chosen cards into your hand and the rest on the bottom of your library in a random order.