Y'hebi N'Caoo are the result of allowing a personification of madness to host your body, usually done by becoming a disciple of a lord of chaos or madness. They have deep sunken eyes, usually, bits of flesh from the cheek come down to form a movable, tentacle-like, mutton chop kind of thing. They always seem to have a greenish tint to them and will have a strange eldritch smell, even if the smeller is unaware of the Y'hebi's presence.

Unknown Presence. The Y'hebi N'Callut can hide in a crowd, as a disguise self- invisibility type concentration spell. It's functionalities act like an invisibility spell, yet it acts like a disguise self, essentially, disguising itself as a civilian, unnoticed by many civilians, until the concentration breaks. The only one able to see through the ruse is the target, the individual the Y'hebi N'Callut is seeking out, which makes the Y'hebi N'Callut a very useful asset as a creature of stealth and underground societies.

 Sneak Attack.  If the Y'hebi N'Callut is attacking someone without their knowing, they get an extra d4 to their attack damage