This continued until I found a secluded area with a prison in the Dungeon. I don't know how I didn't notice it right away? Everything suddenly changed. I gave the entire army to Godric. After all, he is only nominally a level 20 hero, but in reality, he is level 30. It's not so scary with him.
The garrison surrendered without a fight. The level 20 Knights hid. In the castle, a level 5 Necromancer trembled with fear, despite having a decent army. I easily captured the Knight castles. Only with the last one, which Rutger was defending, did Godric have to struggle. Godric's advantage in upgrades helped. After visiting the tree that reveals part of the map, Faidaen appeared. I found Elaine in a Necromancer castle with an immoral Necro-Knight army. Even Zehir managed to defeat her.
My 3 heroes visited all the upgrade locations. Godric and Zehir reached their maximum level. Moreover, there are 2 level upgrade locations on the map. Only Faidaen could not be upgraded further, as he already had level 33. There were no problems with Markel.