Finally, I found the time to finish this mission. It turned out to be too late to kill the blue faction – you suffer significant losses, and then, even with three castles, it takes more time to build up new forces for the main battle than if you were building up from two castles, but without fighting.
Ka-Belekh is, of course, overpowered, and the main surprise was the phoenixes (I was almost shocked when they appeared after the dragons were destroyed), but I still managed to defeat him (I'm attaching a replay of the battle). After this victory, I was quite puzzled by the fact that Sigrif stopped being my hero and switched to the orange faction – I decided that this was some kind of bug. I thought that, on the contrary, after the victory over Ka-Belekh, all the forces and heroes of the blue faction would become mine, and I would have to urgently mobilize them, bring them in, and prepare Sigrif for the main battle with the super-powerful Duncan and Faidaen (level 40 heroes with thousands of level 7 creatures), whose forces I hoped to weaken first with small forces of auxiliary heroes using "hypnosis" and "berserk" (for this purpose, in addition to the existing demons, I prepared another extra demon and two undead).
But then I discovered that if I continue to play, Duncan and Faidaen will appear in the Duchy of the Deer on the next turn. Moreover, these guys didn't even want to come out from behind the green gates until I retreated with the demon that was guarding the exit from the Duchy of the Deer from unwanted guests and opened the way to the castles for them; only after that did they come out behind the gates. These guys turned out to be weaklings compared to the forces of my demon – I killed them both in one turn without much effort and without even thinking about losses, although I could have done without them (I'm attaching the battle with Duncan, but I simply forgot to save the battle with the elf – it was not interesting and simple).
I was afraid that Faidaen and Duncan would turn out to be too easy.
Thank you very much for the test; there is still a lot that needs to be fixed. I'll take a look later at how I managed to hold out against Kha-Belekh.)
Added 1 minute ago
By the way, regarding the "extra" one, I got rid of all the creatures except for one imp, but I still can't send them through the portal a second time, and if artifacts are interfering, then they still can't be gotten rid of – you can't give them to anyone, there are enemies everywhere, and you can't sacrifice them either – the race is evil, and the altar requires creatures.
P.S. Here are a couple more battles with neutrals that I liked:
It was the imp that you needed to get rid of. The artifacts have nothing to do with it
