Nkala
Image © @a-book-of-creatures, accessed at A Book of Creatures here
[I have complained that there’s a paucity of good books in English on native African religion and folklore. Many of the books that do exist are about witchcraft, which means that its easier to find decent references about spirit guides and familiars than it is to, say, trace how exactly a mythological entity has been warped into a living dinosaur.]
Nkala CR 8 LE Outsider (extraplanar) This dark colored creature resembles a crab the size of a dog. It has two heads, one at the front of its body and one behind, each shaped like the head of a hippopotamus.
Nkala are creatures native to the Plane of Shadow, popular among evil spellcasters as assassins. This is due to their diet—nkala feed on the shadows of living creatures, killing them in the process. A creature killed by having its shadow eaten shows no outward signs of violence, only the absence of a shadow in even the brightest light. A nkala can survive on the shadows of mundane plants and animals, but creatures with more Charisma are more appetizing to them, and they will happily enter partnerships with wizards and witches to access higher quality prey.
Nkala on their home plane maintain hunting territories in areas of the Plane of Shadow that are dark, but not too dark. They need some light sources, after all, to cast the shadows they crave. Nkala can speak, albeit somewhat clumsily, but most of their territorial displays include high-pitched whistling. Similar sounds can be used to draw a nkala out of hiding, as it may be fooled into believing there is a rival it needs to fend off. Kytons sometimes use nkala as living torture equipment, but nkala may try to take bites out of their shadows as well.
