Nyxians are humans or elves that have been captured by wandering spectres and dragged into the Realm of Nyx. After a while people that knew them on Valeria give up searching and the person captured often turns to despair and anger. In the Realm of Nyx these emotions, over time, slowly warp not only the person's mind but also their physical bodies until they too are considered monsters by anyone on Valeria. This is one of the ways Nyx is preparing for the next invasion on Valeria.
Once the captured person accepts their fate and gives in complete to Nyx they are rewarded with the knowledge of Nyxian magic, the ability to create, control, and manipulate shadows.