Teferi, Time Raveler

Force each opponent to play the entire game at sorcery speed and half the interaction in Magic simply stops working. Counterspells go dead. Flash blockers can no longer ambush. Instant-speed removal held for the crucial moment becomes a card that only fires on its owner's turn, after the window has closed. That single line of text, arriving cheaply and at four loyalty, folds a control lock and a proactive threat into the same permanent: it pre-empts every reactive answer before opponents have meaningful board presence to swing back with.

Everything else on the card exists to keep that lock in place. The plus quietly hands its own controller the freedom it strips from everyone else, letting sorceries flash in; the asymmetry is the entire point of the design. The minus bounces any artifact, creature, or enchantment (a nonbasic land creature or a planeswalker with those types is fair game) and replaces itself, answering the very permanents an opponent would deploy to chip at the loyalty. It came out of an era that pushed static-heavy planeswalkers hard, and it is the one that proved the style had gone too far: bans in multiple constructed formats followed, not for oversized loyalty numbers but for warping how interaction itself could function. The friction it deleted from its controller's plan, and imposed on everyone else's, was the problem the ban lists eventually addressed.