Nobody is quite sure what the Skiá are or where they are from, but they inhabit the Everdark, drawn to life but repelled by light. Any soul who is unfortunate enough to find themselves stranded in the swirling thick black of the Everdark will never be seen again - not alive anyway.
The Skiá have been here longer than we have. While they are formless at first, the longer you look at them, the more they begin to take on a more recognisable form. It appears different to everyone, but all feel drawn toward them. Compelled to follow the glowing manifestations before them. While they cannot interact with the physical world, they can however ineract with your spirit. It will pass through walls using the shadows to move, seeking out the energy it needs to feed upon. Once it takes hold of you, it drains you of yourself, till only an empty husk remains. You and the Skiá become one. It develops a more humanoid shape. The light of your spirit glows brightly through its chest and head. This is when it is at its most dangerous. It can now physically interact with the physical world. Destroyed walls, extinguishing flame. Killing all it encounters. Adding more to itself, growing in size until it becomes a disturbing manifestation of the lives its claimed.