Can I see this artwork? What's the situation with Haven and the demons?
Actually, a wild idea came to mind - since Heroes 5 is so similar to Heroes 3 (armies, number of magic schools, etc.) and so different from the lore of Heroes 6 and 7, you could create a mod called "Axoth" - NWC actually wanted to continue the fifth part in this world, and anything from there could have crossed through the portals from Enroth to Axoth - i.e., it would be a kind of fusion of parts 3 and 4, which are connected by lore. Well, this is just something to think about in my spare time.
Added 1 hour 30 minutes ago

Блистает там воздушностью прогалин.
Но между кедров, полных тишиной,
Расщелина по склону ниспадала.
О, никогда под бледною луной
Так пышен не был тот уют лесной...