Novablast Wurm

Most board wipes ask you to break parity yourself: you cast Wrath of God into an empty hand and hope to rebuild faster than your opponent. This one folds the parity-break into the attack trigger, and the timing is what makes it brutal. The trigger goes on the stack when you declare the attack and resolves before blockers are ever declared, so there is no chumping it: every other creature dies first, and the prospective blockers die with them. Removing the Wurm in response does not save anyone either, because the trigger is already on the stack independent of its source; kill the 7/7 and the board still gets swept. The design trades the flexibility of an instant or sorcery for a self-justifying engine: the same body that resets the board is the only thing left standing on the far side of the reset, and it does it again every combat. The cost is where the friction lives. Seven mana, two double pips, and a body that has to survive a full turn cycle in play before it can swing at all. That delay is the honest part; the wipe is unconditional once the attack is declared, so the only real window to interact is before attackers are declared, either the turn the Wurm lands or before it swings. It inverts the usual sweeper math: you want the table clogged when you swing, because the more creatures on the other side, the more the trigger does for you.