Man, I am amazed by your army, I had only 75 titans and some crap units on hard difficulty and still managed to win this. The hardest match I have ever played, the fight last like 30 minutes with lots of lags. When I won, the game bugged and I couldnt see the ending scene and couldnt finish the campaign. I beat Biara 4 times with some changes and still got the bugs. Btw, with Zehir you dont need big army :D
Battle looks pretty easy. I don't quite understand how chevaliernoir got 75 angels to kill 87 demons in one blow. I don't think the stat differences between your Zehir and AI Biara were that great.
If you look, Warcraft 3 copied everything from heroes series, but to a RTS format(heroes, monster camps, heroes equipments, hiring heroes from tavern).WC 3 didn't had heroes units.