You need to have Fiery Confluence on top of your deck for this combo to work.
Activate Codie's ability to add five mana.
Codie's ability will trigger, exiling Fiery Confluence from the top of your deck.
Worldfire will resolve, taking all players' life totals to 1 and exiling all players' hand and permanents.
Cast Fiery Confluence without paying the mana cost with Codie's ability, dealing 1 damage to the opponent.