During the Conspiracy Theory quest, you will have talked to Dethmold and learned that you will need four items in order to remove the cursed mist from Aedirn. One of these is a pair of chainmail worn by Traut, the rebel guard in the cellar beneath the tower. If you have been following along with this guide so far, you should have already defeated him during your visit with Dethmold’s soldiers. In this case, you can simply return to Dethmold with the good news and be on your way towards finding the other three artifacts.
If you have not yet completed the quest, you can find out more information about your opponent by speaking with various people around the camp. Talk to Sven during the Butcher of Cidaris quest to find out that Vinson Traut’s armor has been enchanted. Head over to the far right side of the camp to find an NPC named Zyvik wandering around the general area. Speak with him to learn more about the armor and the warrior himself. He will confirm that Traut’s armor has indeed been enchanted with some sort of magic.
Finally, if you have worked on the quest The Blood Curse, you can speak with the Visionary to learn a little more about the armor itself. You will find that the armor is called Seltkirk’s Armor. When you are ready for the battle, head to the rebel headquarters in the cellar by speaking with the prostitutes at the brothel outside of town. You will have to enter a secret password in order to progress through this part. See the previous guide for instructions on learning the password, finding the cellars, and defeating Traut to get his armor.