You clearly have some mod/map that replaces the original Zehir's file, which is why his specialties basically don't exist, so to speak. The best solution is to just keep only this campaign from the maps on a completely clean game.
I took out the red one with Freyda in the stronghold too, there were 55 paladins, 9 left) and 100 crossbowmen remained. Didn't manage to gather enough angels. Lost everything else, didn't even buy the Griffin building. Honestly, he could have been taken down with Arantir with minimal losses, but I wouldn't have made it back in time turn-wise, I was using him to take territory before the external garrisons, cleared the whole center, but overall I have a slightly earlier save, if I can't defeat the purple one, I'll go back. Not working out with the purple one yet) he moves way too often, considering I have Expert Sorcery, and he moves like 3-4 times while I move twice (the hero, I mean). And with the buffed luck they're really something, this time I'm having no luck with artifacts at all. Last time I had the Necromancer's Cloak and their staff too, plus a ring for -2 luck, and now just +1 HP and magic resistance on the map)) built catapults by the way. All heroes show medium difficulty, but it's not working out with Arantir yet, I don't think Freyda will do it either, only if I manage to take down the ballista on the first turn, and that's not guaranteed. The ghosts apparently forgot how to dodge by the way 😂 they dodge 20% of the time in battle with him) even the vampire doesn't help them survive. Using Banishment of course) I'll probably go back to the old save, by that time I'll have 100 paladins, which I think might help take him down, since right now I have 45. Without losses and with the next growth it'll be exactly 100.
and who comes after the purple one?)