Niv-Mizzet, Supreme

The Firemind's guild-lord identity fully inverted: where earlier versions of Niv-Mizzet paid you for every spell cast, this one pays you back the spells themselves, but only the ones that live between two colors. That gating clause is the whole engine. Jump-start already exists as an Izzet mechanic that recasts a spell from the graveyard by paying its cost plus discarding a card, then exiling it; this reads that ability onto every exactly-two-color instant and sorcery in your yard at once, turning a five-color mana base into a rebuy machine for gold spells specifically. The two-color restriction is doing pointed work: it locks out the format's most efficient monocolor removal and card draw, so the payoff scales with how deep your deck commits to multicolor spells rather than raw good-stuff. Hexproof from monocolored is a matching piece of texture, a keyword that shields the body from the mono-white and mono-black removal that dominates while leaving it exposed to the gold and colorless answers a five-color deck is already inviting to the table. It is a rare lord whose evasive 5/5 flier is almost the least interesting thing printed on it; the real question is whether you can build a spellbook where every card is worth two colors of investment, because that is the only library this dragon knows how to read back to you.