Practice mode

Feature allowing you to attack your own base or allow clan members to attack it to test for weaknesses. No loot or trophies to be gained or lost. To prevent people from copying war opponent bases and practicing, it should cost the attacker their troops. Yes, I realize this has been suggested many times before.

Confirmation needed, but probably ruled out.

This idea is too exploitable. You could set the base to match one of your opponents from war and practice until you get 3 stars. Not going to happen I'm afraid.