Lords of Creation: Ancients of the Void
The Reapers are the final evolutionary stage of the Wayfinders. Once their bodies have returned to ash, their souls are freed to be imbued with greater power by Kereth. This process occurs in the Soul Fields and takes a shard of Kereth a brief period of time to do.
Reapers have a physical body that is somewhere between the astral bodies of the Soul Fields and a mortal body. They are capable of altering mortal perceptions of their form, though all Fabled Races see them as they truly are, which is a being made of light in the form of a Wayfinder. Their bodies are stronger than even a Wayfinders, and Reapers do not age, though they can be killed.
While a Reaper can alter its appearance, it rarely appears to be more than the race who’s territory it currently occupies. Reapers appear to be exceedingly ordinary, and races below magical have a hard time noticing their presence at all. A Reaper can be interacted with on the Material Plane, but it takes a Magical Race focusing on the Reaper to notice it, identify it, and interact with it. Reapers can, though rarely do, interact with races below Fabled, but even then, the person being spoken to rarely remembers the Reaper longer than a few moments after the interaction ends.
Reapers, like Wayfinders, practice the Twisting Path, though their staves are made of Lantern Light, and can be incredibly deadly. Reapers do not share the qualms that Wayfinders do about killing. This staff is hidden within the Reaper, unless it is summoned to be used.
The Reapers additionally have a miniature version of Kereth’s true lantern within them, which allows them to sense the presence of mortal souls, guides them to departed souls, and stores these mortal souls until the Reaper can return them to the Soul Fields. They possess infallible navigation due to their ability to observe the world from the Soul Fields, though the underground still gives them issues.
Reapers don’t eat or breathe, so merfolk and locathah souls are no more problem than Skizzik.