The Hero's Path

This is the best scenario I've ever played. It's hard to even call it a scenario; it's more like a DLC for the game or even a separate game. I would gladly donate for such work, but I don't see where to do it. I have a question about completing the game on "extreme" difficulty: What are the stacks that appear as you move around the map, something like an ambush for the player? A stack of undead, Dungeon creatures, or a legion of golems – how can you defeat them?

Added after 3 hours and 48 minutes
I found a bug related to the "Rescue the Team" quest: why can ordinary zombies, skeletons, and ghosts inflict blindness in tactical mode?