({9} magic symbol) ({R} magic symbol) ({R} magic symbol) ({R} magic symbol) ({R} magic symbol) ({G} magic symbol) ({W} magic symbol) plus enough mana to pay for commander tax, if applicable available.
Steps
Cast 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.
Cast Marath from the command zone by paying ({R} magic symbol) ({G} magic symbol) ({W} magic symbol) and commander tax, if applicable, causing Marath to enter the battlefield with a +1/+1 counter on it for each mana spent to cast it.
Activate Marath by paying ({1} magic symbol) and removing a +1/+1 counter from it, dealing 1 damage to any opponent.
The opponent loses the game due to having zero or less life.