Thanos, the Mad Titan

A deathtouch, lifelink 4/4 across three colors carries its own weight long before the rainbow sweep ever comes online: it trades up against anything and gains life while doing it, a fair aggressive threat by any measure. What hides underneath is the engineering feat. The power-up ability demands one Infinity Gauntlet's worth of mana (all five colors plus colorless) and, in exchange, delivers a one-shot board partition by parity. Choose odd and every other creature with an odd mana value dies; choose even and the ones with even mana value go instead (zero counts as even, so the sweep can reach any creature that costs nothing to cast). The discipline that pays for a color-locked asymmetric wrath is that it fires exactly once: the parity call is a single irreversible read of the board, deciding which half of the opposition to erase and living with what stands. Framing the payoff as a full rainbow assembly makes it a race rather than a repeatable engine, and casting Thanos and firing the sweep on the same turn is cheaper than deploying him early and holding it in reserve, which rewards the aggressive line. The real trick is disguising an asymmetric wrath as a curve-filling beater, so the card threatens two entirely different games depending on whether you ever reach all five colors. Few creatures ask you to build both a functional curve and a working five-color manabase at once, and fewer still make the second half feel like a reward rather than a tax.