Niv-Mizzet, Supreme is a rare Legendary Creature — Dragon Avatar card from March of the Machine: The Aftermath (MAT), collector number 90. Current market price: $0.62 (foil $0.65), TCGplayer market prices via Scryfall.
Flying, hexproof from monocolored Each instant and sorcery card in your graveyard that's exactly two colors has jump-start. (You may cast that card from your graveyard by discarding a card in addition to paying its other costs. Then exile it.)