I never had that problem, because I started out with three rules in no particular order:
- Every turn starts with a mandatory roll, and players can't otherwise roll unless they use Fractured Powerstone (which can be cast and activated for free and at instant speed [activation with permission if it's not your turn], but can't produce mana and can't otherwise be interacted with).
- Every blank face was a mandatory re-roll (whiffing is no fun). As you can imagine, we went through the Planar Deck FAST.
Unfortunately, I never got around to improving on that initial premise...in fact (despite the description), this is the first time I've written those other two rules down.
As an interesting side note, PLANECHASE Commander was my group's only format to be hard-locked to exactly four players per session, as a consequence of PLANECHASE rules mandating a minimum Planar Deck size based on the quantity of participants.
Once all of the new cards are revealed, I'll
revive that old CPD; if there are new Phenomena, I hope it will be an even number so I can update the player quantity lock accordingly.