Tamiyo, the Moon Sage

The plus ability is the engine the whole card hangs on: tapping a permanent and denying it the next untap step is a soft lock that scales to anything, not just creatures. Point it at a manland and it stops attacking; point it at the opponent's only blocker and your team gets through; point it at a mana rock and you tax their next turn. Crucially, the lock is repeatable, so a Tamiyo left unanswered turns a single permanent off indefinitely while she climbs. The minus draws off tapped creatures, which folds back into the plus: every attacker the opponent commits, every dork they leave down, becomes cards in your hand. That feedback loop (lock a thing, refill off the things that are tapped) is what makes her a control finisher rather than a tempo nuisance, and it asks for a board you can grind to a standstill. The ultimate is the rare blue emblem that closes the door for good: unbounded hand size plus recursion of anything that hits the graveyard, the kind of inevitability blue otherwise has to assemble across multiple cards. She belongs to a small class of planeswalkers whose plus is a removal-adjacent answer rather than a board-building threat, which lets her defend her own loyalty while still advancing toward a game-ending state.