I immediately took Victor, who, as it turned out, was a formidable attacker in Chaos (Ice +10 also affects the ballista) (I needed Andreas with the same specialty, since Victor appears more often in the tavern). He quite quickly captured the Scroll of Berserk in the first few days, but couldn't use it – the hero with a deck of cards had 40 mana, which wasn't enough.
In general, Victor couldn't go very far; he stayed and defended, occasionally summoning neutral creatures and ambushing careless demonic heroes. He cleared a path to the upper Castle, but couldn't go any further than the passage where the manticores were stationed – demons kept coming, so he had to defend the Castle. He couldn't leave the Castle.
I leveled him up to 21, and the demons were afraid to show themselves, but as soon as he moved away, they appeared. And the scout, Ellaine, was suddenly trapped by the growing djinns.
I bought Frida, leveled her up, freed Ellaine, and she came as a replacement, while Victor went for a walk to the first Castle, killed a Necropolis and a bunch of neutrals, but couldn't handle the Astral Gate. Frida isn't Victor, but she withstood two battles against 30 Devils/80 Unicorns, and the third time, when a yellow level 10 hero with a lot of troops and medium difficulty appeared, only 8 Adepts remained in the field battle, so she didn't accept the field battle. That demon summoned troops up to high difficulty and attacked the Castle (30 Devils, 90 Imps, 800 Imps, 500 Dogs, 70 Unicorns), but he didn't have a catapult and gave 70k experience. Frida defended with a novice's stick, the Armor of Fearlessness, and a couple of other minor items, while Victor had many artifacts, but he was far away. He had the Berserk, but Divine Vengeance, which negates curses, was just as good. The bonuses to luck near the Castle helped a lot.
Meanwhile, Victor killed everyone and approached the last demonic Castle like this (with a developed counterattack skill without supervision) with 70 Angels and Unicorns) http://c2n.me/3SvMQSU, http://c2n.me/3SvOh3a
The guard at the Astral Gate is stronger than the garrison. The demons themselves didn't really like Darkness, they preferred explosions, meteors, and chain lightning, which made things a little easier