Karn, Scion of Urza
Two distinct decks live inside one four-mana planeswalker, and they almost never overlap. The +1 is a dig with a delayed payout: you reveal the top two cards, the opponent decides which one you keep now, and the rejected card waits in exile under a silver counter until the -1 pulls it back. Cashing both cards therefore costs two activations across two turns, which is exactly why the ability rewards fair, grindy shells with the loyalty and the patience to run the loop. The silver counter is a bespoke redemption tag that only this card's own -1 can retrieve, so the engine stays honest: the opponent picks the worse card for you to keep first, and the better one sits stranded until you spend a second activation on it. The -2 answers to none of that. On a board dense with artifacts the Construct token scales without a ceiling, handing an affinity-style deck a finisher that taxes none of its colored mana. The two halves rarely both matter in the same list, so a deck decides which Karn it is running before the game starts rather than during it: card-advantage engine or on-demand threat. A colorless cost makes it one of the few planeswalkers any archetype can splash, and that split kit is why it turned up in decks that shared nothing else.
