Doms 2 AI got many major flaws, like it wont build castles, or enough castles, it builds loads of useless troops etc. etc.
I never had problems beating the hardest AI at all....
I hope that these errors will be fixed in Doms 3, if there will be a Doms 3 at all
"Training is principally an act of faith. The athlete must believe in its efficacy: he must believe that through training he will become fitter and stronger, that by constant repetition of the same movements he will become more skillful."