Board Thread:Lore Discussion/@comment-72.241.239.167-20140311020135/@comment-192.76.8.39-20140829142652

If it's connected to Magnus, it's almost certainly connected with his departure; the casting-off of the Aedric nature he was nearly trapped in, perhaps, or when he punched a hole and entered aetherius, some of aetherius likewise entered mundus.

However, it's most likely KINMUNE, who was absolutely definitely buried under Sarthaal, by Ysgramor, at the right time.