Lavabrink Floodgates

A board wipe with a fuse everyone can touch, and the whole design lives in that shared fuse. It does not fire until three doom counters accumulate, and each player's upkeep hands the active player a choice: arm it by adding a counter, defuse it by removing one, or leave it untouched. That optional move per turn converts a symmetrical six-damage sweep into a slow clock nobody controls outright. Anyone can advance it toward detonation; anyone can walk it back on their own upkeep, which is why it rarely fires on the timeline of whoever first started arming it. But the payoff never leaves your hands: the artifact's controller is who sacrifices it and controls the six-damage trigger, so the negotiation over the counters is a negotiation everyone participates in for a weapon that belongs to you. The mana ability is the pressure valve that keeps the artifact from being dead while the counters oscillate. Tapping it produces two red between untaps, so it functions as a Rube-Goldberg mana rock that occasionally threatens to explode. Because the sweep is symmetrical and telegraphed several upkeeps in advance, you want the count to cross three when your own board is light on creatures, which reframes the card from an answer into a piece of leverage: the counters are a promise or a threat you keep adjusting until the incentives to detonate briefly outweigh the incentives to stall. The six damage is the payoff; the negotiation over the fuse is the mechanism.