[Radek]

Reentering Erathsmedor's room from the dungeon does not work. The same result: silent Erathsmedor plus Kol gazing on it. Nevertheless, the following seems to work:

1. Flip the lever and enter Erathsmedor's area
2. Peek your nose into the Erathsmedor's room. Let the dragon kill Kol.
3. Return to the lever. Create portal and teleport away.
4. Do what you need to do and teleport back.
5. Erathsmedor will now continue its script. You can tell the dragon "Elseramavin" and give it the shroud. The game runs normally.

Conclusion: You must trigger the scripts of Erathsmedor and Kol before teleporting away. If you teleport away before triggering the scripts, the scripts get lost and you will have to kill Erathsmedor. Reentering Erathsmedor's room from the dungeon does not work.