In my opinion, demons are the weakest. But only until they level up and get their super ability. True, they have Daleb with a terrifying ballista for rapid development. Yesterday, I played with a friend as demons. And on the first level, she received a ballista. With a double shot, she instantly destroys neutral creatures. And the enemy hero also got a good dose of it (he showed up in the second or third week) - with its help, she quickly eliminated 200 gremlins and their support. If he had come to me instead of my friend - the warlock, we would have had to start a new game.