Sarulf, Realm Eater

The design tension here is that a symmetrical board wipe wants to be cheap and reactive, but a creature that grows off attrition wants the game to grind. This 3/3 resolves both by feeding on the same permanents it will later exile: every opponent's permanent that dies from the battlefield adds a counter, and each counter raises the mana-value ceiling of the eventual sweep. The catch is a hard timing gate. The exile trigger fires only on your upkeep, and only if you empty every counter at once, so the reset is a delayed, all-or-nothing detonation you can only choose to trigger once your upkeep arrives. That upkeep-only window is what holds a self-scaling wrath in check: you cannot detonate mid-combat against a lethal swing, the size is locked to whatever attrition has already happened, and if an opponent removes Sarulf before your upkeep the whole threat evaporates, counters and all. Because the sweep exiles, it sidesteps death triggers and indestructibility, and it spares lands and Sarulf itself, so the reset leaves you with a body and a mana base while every other nonland permanent below the threshold you built vanishes. The whole card turns on that mana-value cap, which rewards a patient grind over raw tempo: you assemble the sweep one dead permanent at a time, then survive a turn holding a threat that telegraphs itself a full rotation before it goes off.