Shaden is the cave on the border between Roth Roryn and Armun Ashlands. The Andothren smith gives you a quest to find a crusader of Arkay whom he sold a bad cuirass. The Dunmer in The Grey Lodge Inn mentions that the crusader went into Shaden. His body is laying outside of the cave, killed by kagouti. In any case, the player is led to explore this cave and experience its numerous bugs. One of the most notorious ones is mentioned by the cave's UESP page:
Due to vanilla dialogue filtering, all TR Morag Tong masters can hand out vanilla writs and reward you for their completion as long as the related topics are available. It doesn't work vise versa and would require adding a lot of new dialogue in all TR writs.
