it was a funny bug. in the "Bowl of Thunder" scenario, I had a hero of level 18, with an army of about 500 trappers, 300 free centaurs and warmongers, 93 daughters of the sky, 34 executioners, 22 wyverns (which had 2 upgrades), and 10 free cyclops. I entered the dungeon and saw a group of skeletons under a griffin. The difficulty was set to "impossible" ))
Added after 1 hour 5 minutes
I still don't understand: why did the developers make such a week with such a description?!