Hello,
I find the idea good and joining that of pluging "imperium". I think this idea of conquering territories would be reinforced if players could only build in his territory and if ever his "large banner" is destroyed then the decay would be active making his constructions easier to destroy. This would make opponents find and destroy the large banner first.

Hmm, It will be pretty tough to implement but the idea is a good one. I need some time to understand how to do it right...