Lethal Vapors

Most board wipes end the game state once and let it rebuild. This one freezes it indefinitely: every creature that touches the battlefield is destroyed on entry, from either player, with no expiration. The trick is that it gives you no clean way out. The shutoff costs zero mana and any player can press it, but doing so skips the activator's next turn, so the enchantment writes its own punishment into its own answer. That penalty clause is the whole design problem solved in one line: a perpetual creature-destruction lock would be miserable if it were free to dismantle, so the only key to the cage costs you a full turn of the game. The "any player may activate" wording is the wrinkle that turns it from a private prison into a shared one. Either side can choose to eat the turn-skip to break the stalemate, which makes the enchantment a negotiation as much as a card: whoever wants creatures back first pays the toll. Among the early black enchantments that punish creatures wholesale rather than once, it stays the bluntest, a stax piece that does not ask for synergy so much as it asks both players to live without their creatures until somebody blinks.