Hmm! I assume you might have designed this in a hurry. Because you'd probably have this:When CARDNAME enters the battlefield, each player's life total becomes 1.Players can't gain life.Creatures can't attack.Hmm. I like what it's trying to do here. But it seems too easy to kill opponents like this, considering you're at least a red player. Get to 9 mana, cast this enchantment, then use the last red mana for a Lightning Bolt or other burn spell.Worldfire at least makes it difficult by exiling everything. Perhaps you can do this:When CARDNAME enters the battlefield, each player's life total becomes 1. Then end the turn. (Insert text here that reminds you what ending the turn does.)Insert rest of card text here (creatures can't attack and players can't gain life).
Admittedly, I was in a hurry and forgot all about Worldfire. Oops.