Heart of Chaos

Everything seems good, but... one of my heroes, a weakling, died early on, and he was the only one... and I'm being attacked from two sides with endless waves of enemies. Chaos doesn't care. His enemies are no match for him, but to get rid of the demon, I need to take all his cities, and the dark elf isn't exactly happy with my dominance on the map. And as a result, I'm stuck: cities in my rear are constantly being captured, and if I go on the offensive, the demon pushes back everything because, although the hero is very powerful, he's alone.