Getting rid of copper

Just a little tip.

When you've done your best to gain loads of copper but you find yourself the target of an impending attack,
it is of course best to donate your unprotected resources to the alliance.
Copper you can't donate on the other hand. When you see that you can no longer to any research at the alchemist,
have no more recruits to hire or are at your maximum military capacity, did enough advanced training on your champs, ...
there aren't much ways to spend your copper to avoid it going to your adversary.
Best thing you can do is just upgrade your troops in the alliance barracks. It costs a lot of copper,
so normally you won't be able to even upgrade them all.
It's only a hassle @ the deployment part, make sure that your heroes are equipped with the right troops.
If you donate enough resources to the alliance, you should have a shitload of alliance contributions (I have loads)
so there shouldn't be an issue there.

Hope this helps!