Two sisters.

I don't know, maybe I have a different version, but all the heroes would run away from the castle as soon as they were left without catapults and creatures capable of dealing damage from behind the castle walls. In the last battles, I even tried not to kill a couple of dozen spear throwers and one or two Arcomage priests, just to prolong the fun – they don't do much damage (the tent revives more than they kill), and the enemy hero doesn't run away.