Worldfire by paying ({6} magic symbol) ({R} magic symbol) ({R} magic symbol) ({R} magic symbol) , exiling all permanents, all cards in all hands and graveyards, and setting each player's life total to one.
Outpost Siege triggers for each creature you had leave the battlefield this way.
Resolve the first
Outpost Siege trigger, dealing 1 damage to any opponent.
The opponent loses the game due to having zero or less life.
Repeat from step 3 for each remaining opponent.
Results
Each opponent loses the game.
Exile all cards in hands and graveyards.
Exile all permanents.
Near-infinite lifeloss.
Mass Land Denial.
Metadata
In 671 decks according to EDHREC.
Bracket Tag
This combo has been estimated to be Ruthless (Bracket 4+).