Of the various kinds of spirits that exist in the land of Zenoa, Fells are among the most dangerous. They are a type of cursed spirit- Those that are brought forth from remnants of cruelty or death- And usually appear in places where such things occurred.
Fells manifest in the material plane as solid white masks of varying designs. The rest of their body is incorporeal, though they have been known to create a physical body from objects in the vicinity.
Sometimes, large numbers of Fells will gather. Upon doing so, they merge together and form what is known as an Eidolon. These amalgams are far more dangerous and powerful than a lone Fell, so extreme caution is necessary if confronted by one.