Kederekt Leviathan

A board wipe stapled to a body, but the staple cuts both ways. The enters-the-battlefield bounce sweeps every other nonland permanent back to hand, which means your opponents lose their board and you lose yours too: every token evaporates, every aura and equipment falls off, and anything riding a stack of counters resets to zero. The asymmetry has to be manufactured. You want as little else in play as possible when this lands, which is precisely what unearth provides. Casting the eight-mana shell is one game; firing the unearth from the graveyard is another, dropping a hasty 5/5 that resets the table on a turn when you have committed nothing but lands and the Leviathan itself. The end-step exile clause is the cost of that cleaner line, and it interacts pointedly with the bounce: an unearthed Leviathan can never return to hand, because the replacement effect exiles it the moment anything would move it off the battlefield, including its own owner's effects later in the game. So the recursion buys exactly one global reset attached to five points of haste damage, then is gone for good. That is the tension worth admiring: a mass-bounce that punishes whoever deploys it hardest, answered by a graveyard mode timed for the moment you have the least to give back, and explicitly forbidden from looping the trick a second time.