I somehow managed to get through it easily. Maybe because I got into the add-ons first, and then the main game. I immediately went northwest to the Dungeon, captured the town, hired a hero to stay there and deliver troops, and started clearing out the underground. I cleared it out, accumulated some strength by delivering troops from the places where the creatures were born near the Castle. A green hero came from the east, and I defeated him only because Agrael was well-leveled – mainly through opening gates. I went up through the eastern exit, destroyed the eastern Castle, hired a level 17 elf in it, whom I had just defeated, and went to destroy the Castle in the middle. I defeated it, and another hero similar to the first one appeared, but with better stats. I killed him with difficulty, hired him in the Castle, went around the large island, leveled up, and went with one of the recently defeated elves up to the east, captured the Castle (there was someone of level 1 sitting there), cleared out the powerful islands with elves, and with Agrael, I took archers. I went down, took a hero in the Castle, and went to the dragons. I gave the archers away, took the missing troops from the alternative army, and went to the Castle. I destroyed it very quickly. All the troops were leveled up (except for the demons), and I didn't level up the elven Castles except for the buildings with elves and those that generate money. The army wasn't very strong, the difficulty was medium, but I defeated it in five minutes using only gates.
I read the thread and got upset – everyone was struggling, and I somehow managed to get through it easily. And I like challenges!)