And there's a theological question: what's the point of storming the Underworld? By killing a demon outside the Underworld, you send it there, where Urgash resurrects it (especially in Heroes 6, where Zana tells Kirill that if they are defeated, Urgash will resurrect them). Demons turn out to be immortal in the world of Heroes, making the storming of the Underworld pointless.
And there's a theological question: what's the point of storming the Underworld? By killing a demon outside the Underworld, you send it there, where Urgash resurrects it (especially in Heroes 6, where Zana tells Kirill that if they are defeated, Urgash will resurrect them). Demons turn out to be immortal in the world of Heroes, making the storming of the Underworld pointless.