Searching for the Rune Sphere (remake)

I replayed it for the third time. I dealt with the Dwarves after three months. But here's the problem: I took the harness from one of the Dwarf outposts, the axe from behind the Blue Gate with incredibly strong guards, but where is the Rune of Fire (I didn't take it from the Dwarves)?! I would be grateful for a hint, because I'm running out of strength.

Added after 15 hours 27 minutes
I barely found the Dwarf treasure in the eastern Dungeon, the entrance to which is through an inconspicuous portal. I went there hoping to find the rune and failed because of the guards. Against my 500 monks, there was a defense force of about 700 dragons, 1300 jarls, 2000 priests, 4900 berserkers, 10700 bears, 14700 spearmen, and 16600 warriors. Although I was an expert in all aspects of Dark magic and even had Sandro's cloak, I couldn't withstand such a large number of units. Is this a bug, or another "feature" of the author, like the portal to the city and the constant generation of Dwarves?

Added after 21 hours 0 minutes
Compared to the guards of the axe and especially the rune, the final boss, King Tolgar, is just a harmless baby.

Added after 2 hours 58 minutes
On the third attempt, I completed the map with a hero in 157 days (I was given a cyclops). The author clearly overdid it with the guards of the axe and the rune. It's clear that the earlier you come to them (last time I got there in the 8th month), the fewer there will be, but still, it would be good to have 500-600 monks. Tolgar is stubborn, but quite beatable. I went to him with about 950 monks, 650 archers, 200 knights, and 35 archangels. The map is challenging and evokes mixed feelings. On the one hand, there are interesting battles and overall tactics, and on the other hand, there are the author's "features" like the portal to the city, the generation of Dwarves, the inadequate guards of the axe and especially the rune, and minor things (the absence of a church, the remoteness and excessive protection of the mentor, etc.). Nevertheless, thank you to the author for the work.

Is the author planning to combine these maps into one campaign? That would be nice.

The map is completely unplayable on Hero difficulty.
You can't develop on the small starting area. There are hordes everywhere. There is no way to swim. What should you do on the starting area? Waiting and accumulating an army is not an option.
Here is an example of a gold mine. What is it for, I don't understand. By the time I can destroy this stack, I won't need it anymore.