Each opponent loses the gameExile all cards in hands and graveyardsExile all permanentsNear-infinite lifeloss for all playersMass Land Denial
How it works
Cast Finale of Promise by paying 9, casting the instant that deals damage or causes lifeloss and Worldfire from your graveyard without paying their mana costs.
Resolve Worldfire, exiling all permanents, all cards in all hands and graveyards, and setting each player's life total to 1.
Resolve the instant that deals damage or causes lifeloss, causing each opponent to lose at least 1 life or be dealt at least 1 damage.
Each opponent loses the game due to having 0 or less life.