Surrounded by monsters that thrive on human souls, the forest tribes of Overgrown Secrets have a secret weapon: the Anhui. Anhui are six-limbed monsters of green chitin and bone. Their parasitic larva transform its host into a powerful warrior for a short time before killing them. The forest tribes intentionally raise and keep these monsters to produce powerful warriors in times of distress, known as "Bearers". Each tribe has a "Keeper" that tends to its dormant and caged Anhui until they are needed.
Anhui didn't actually see much screen time in Overgrown Secrets, but they easily could have, and they had a strong effect on the setting.