Didn't SOD_SP help? That's strange.

This is not the first map where SP doesn't help when experience overflows.

It's not useless: the guardian of the passage in cell 2,8,1 requires you to have this hero.

The trick is that, having a Dungeon Lord, you simply enter the last Castle and get the victory because you killed all the opponents. =)

I repeat: since the author himself completed the map, there are no critical errors there.

You can start the map as red or blue, but the last opponents are only blocked by the guardian for the red player. So, there are critical errors xD When you complete it, write how you got past Lavia Mron. I had to add a flight spell and then I finished the map.

Added 4 minutes later
I watched the author's video, and he has a flight spell at the end of the game; it's interesting where he got it.