Jodah, Archmage Eternal

The cost-replacement clause is the whole engine, and its genius is that the substitute payment is fixed regardless of what you cast: five mana, one of each color, buys any spell in the game, from a one-drop to a fifteen-mana eldrazi. The Jeskai color of the card itself is a feint. By offering a Sultai-inclusive payment route, this body invites a deck built around the most expensive, most chromatically demanding bombs ever printed and asks only that you assemble all five colors of mana once. That reframes the deckbuilding problem entirely: mana value stops mattering, and the constraint shifts from "can I afford this" to "can I reliably produce WUBRG." Everything downstream follows from that single substitution, which is why this commander became the engine of choice for big-mana five-color piles long before later, splashier WUBRG payoffs arrived. Crucially, the substitution is a static ability, not a tap ability that demands a turn's patience: with five colors online the moment Jodah resolves, the discount is live immediately, no summoning-sickness tax, no waiting to untap. The 4/3 flying body is almost incidental, a clock that happens to come attached, though the evasion does mean an unanswered Jodah threatens to end games on its own while the cost engine hums. What balances it is the obvious target painted on a four-mana legend: kill Jodah and the whole enterprise reverts to paying full freight, so the deck lives or dies on protecting the one card doing all the accounting.