Very decent game, but AI is horrible - clerics heal randomly, they seem to be stuck on a certain, random hero instead of healing everyone equally, not to mention the fact that they often don't heal at all. You should make them heal all the time unless nobody needs it - then they should switch to DPS.
Also, targeting seems random at best, instead of going for the closest target, they seem to go for a semi-random one and go there no matter what - even if there are 10 mobs much closer, and they have to go through the entire map.
Still, 5/5 - very promising game, keep it up :)