Primordial is now using the free-for-all Commander system for its multiplayer mode.
In other words, your deck must still be compliant with the Primordial format deck-building rules (no commander, 1 set, 40 cards minimum, etc.) and your games should look like this:
- 2-6 players
- Free-for-all multiplayer format
- Start with 20 life
- Take turns in clockwise order
- Last player standing wins
Also, as it used to be stated in the Official Commander Rules: “House rules or ‘fair play’ exceptions are always encouraged if they result in more fun for the local community”.