[M]: "Counterattack"

The portal on Mount Arcat is one-time use, right? Rune recall.

No. Caravans won't be able to pass through, but the main character can (it only works in one direction).

Added 7 minutes later
Regarding the art from the dragon set. It's not a mod issue. It only happens on this map. I finished the map, deleted it, and loaded another one – everything is fine. It looks like this: the description of all parts of the set is as if it were a single artifact, like a "necromancer's helmet." All information about the set is missing.