Make a queue button so you can battle your mates. Not a direct battle but like current pvp although without any limitations to any levels.
No gain other than a counter in clan that states how many battles fought in the clan?

It would be a lot more fun to test out decks when you aren't doomed to drop in rank when trying out cards that you aren't sure about investing resources into.
Might create a lot more diversity, when testing without loss becomes possible?