Decided to play through this atmospheric map for the third time. This time, the main hero became Raileg, as the plan was to rely on his ability to reduce enemy initiative. Immediately headed underground to capture buildings and recruit "invisible" troops. Returned to the first guest, having acquired "Pyrokinesis" and "Lucky Mage," and later "Phoenix Cloak." Considering that the elder druids from reinforcements increased magic skill up to 67, the rest of the Walkthrough was easy, and my strategy was correct.
I easily defeated all enemies, including Kana, as I had a large number of troops accumulated from the City of Mages, thanks to "Night Hags," etc. For the battle against Pyrrhus, I simply switched the main hero to Arantir, and then came the most interesting part: In the battle against Udon, if you use "Regeneration," a bug occurs! After the battle, all troops are in the same quantity as before the battle. For example, after the battle, I had 38 monks left (I was tired of simply "raising" them with regeneration), but after the autosave, I had 185 monks again! The same story happened with all troops where I used this spell, and where I didn't, they died as expected! No mods are installed. The battle was in the Human castle. I think this is a bug due to choosing a non-standard main hero, knowing the ending. That's how it is.
Another tip for everyone: if possible, meet enemies outside the castle; this will give you time to capture buildings and gain a good advantage. I didn't even upgrade logistics and still managed to be everywhere on time. There was a "Plague Week," but still, by the end, there were too many troops! Even dragons weren't needed (and black magic doesn't affect them). I defeated everyone on the first try without reloading, and I still haven't found a staff with 20 "Initiative"! In short, the main thing is to have a plan for the game. Good luck to everyone. Thanks again to the author for the super interesting map! I really want to play it again, but with a new strategy and main hero.

I finally defeated Kana, probably on the 30th attempt. His army simply grew tenfold; consider that he was "fermenting" underground for 2 weeks, and I found a Hive there in the library.