Walkthroughs for custom maps.

Cool, I still have a long way to go... But I like the map so far, and it should get even more interesting later.
The author warned about the danger of overflowing experience and skills in the first post of day 1:

Skills have their limits, if you've maxed your skills you will have to skip getting power ups, otherwise you gotta have bad days

Didn't SOD_SP help? That's strange.
You need to ask the author what to do next. His contact information is in the map description, but as I understand it, he doesn't check his email very often now, so you can write in the topic about the map on VK or under the video of the streams on Youtube (then he answers almost immediately). I repeat: since the author himself completed the map, there are no critical errors there.
Well, and ProspectorRT will always help you.

the Dungeon with the hero Motrurgaah opens, but he looks useless

He is not useless: the guardian of the passage in cell 2.8 requires this hero.