It really depends on your play group and how they wanna have fun with this new casual format. For one, we added a CMC minimum to the Signature Spell. It has to be an instant or sorcery with CMC of 5 or greater thus minimizing all the broken combos out there. And we are a casual group by all means which is why we set this rule up within our group. Allows us to have fun with the new format. This would also NOT prevent us from playing windfall in the deck with the new Narset but it will prevent the lock if windfall was the Signature spell.
So, with that in mind.... One thing I'm not 100% on. If we chose a spell with an overload cost, such as say Cyclonic Rift, would the overload cost be affected by the Commander Tax? So the next time it was cast for it's overload cost it would be 9 instead of 7? And I do see that Cyclonic Rift wouldn't follow our 5 CMC rule. I was just using it as an example.
So, with that in mind.... One thing I'm not 100% on. If we chose a spell with an overload cost, such as say Cyclonic Rift, would the overload cost be affected by the Commander Tax? So the next time it was cast for it's overload cost it would be 9 instead of 7? And I do see that Cyclonic Rift wouldn't follow our 5 CMC rule. I was just using it as an example.