Lukka, Coppercoat Outcast

The middle ability is where the design lives, and it is a genuinely reckless piece of engineering: exile a creature you control, then reveal until you hit any creature with a higher mana value and slam it straight onto the battlefield. Most tutor-and-cheat effects police what they find with a fixed cost or a strict cost ceiling; this one polices with nothing but the mana value of the thing you fed it. Exile a standard token (mana value zero) and the floor for what comes out is a one-drop; exile something big and there is no upper bound at all. That chaff-into-payoff conversion made it the engine of a combo built on cheap, expendable bodies converting into a single enormous threat, and the loose "greater mana value" clause meant the deck could be tuned so the smallest input reliably found the largest possible output. The plus ability quietly supports the same plan, banking creatures in exile you can only cast while a Lukka planeswalker survives, which turns the loyalty count itself into a resource lock. The ultimate is an asymmetrical Fireball that only hits your opponents, off every creature's power, but it was almost never the point: the reason to run this was the deterministic upgrade on the −2, not the payoff seven loyalty away. A cheat-into-play effect that keys off a value you fully control on both ends is exactly the kind of design that gets solved fast once someone finds the right bodies to feed it.