http://csclub.uwaterloo.ca/~geduggan/EDH_rules.html
This is a Magic The Gathering casual format that I think would lend itself very well COC style. Instead of "Legendary Creatures" the key would be Unique Characters. So for those not interested in decyphering Magic terms... 100 card highlander decks where your "general" dictates what faction your deck is. Neautral characters can only be played in a Neautral General's deck for example...
What do you think? Fun for casual!