It might be interesting to have a Ranfurly Shield-like trophy that is competed for among the clans.
See the link below for a more detailed description, but the basic idea is simple. The holder of the trophy must defend it from a challenger. If the challenger wins, they get the trophy; if the holder wins, they keep it. You try to hold onto it as long as you can.
A number of issues should be addressed for a successful implementation:
- preventing a clan from refusing challenges (maybe they have to accept a trophy challenge within 2 weeks from their last successful defense)
- required number of clan members involved in the challenges?
- multiple trophies for different timeout/time bank settings?