Shadeling
Shadelings live in places near the Below, and seen only in passing at the edge of one's sight. They are drawn to anyone infected with mindrot and feed of the fumes and decayed mind-matter left behind by the debilitating and destructive disease.
The exact appearance and nature of shadelings is unknown due to the inability of fully and directly observing them. They blink in and out of sight at the edges of one's vision, and are,for the most part, easy to miss. They make no noise, at least not one heared by people. It's unclear whether shadelings are able to interact with the physical world. Some swear to have been touched by a shadeling, describing the feeling as cold and leaving behind a sickly-sweet rotting smell.
Shadelings may appear alone or in clusters, and it seems they are most attracted to the newborn, the sick and the elderly. They might appear in the midst of a fever-dream as hushed, faint silhouettes of smoke and shadow, or so the stories go. And though seen through the edge of sight they appear mostly on the smaller side, in dreams they are described as being as tall as a man, or even as tall as a house.
Just as with everything else, nothing is known of the shadelings' lifecycle. Are they born? Do they die? Can they die? Whether they are closer to spores such as agalin, or more akin to spirit folk of nature, existing outside of human perception but capable to be communicated with, nothing is known for certain.
Diet: feeds off decaying minds weakened by mindrot
Habitat: edge of vision, border between the physical world and the world below