Like a C'Tan.
Like a C'Tan.Khaines just sleeping in shattered form.
Like a C'Tan.Occasionally (when someone is sacrificed to create an avatar) Khaines sleeping consciousness bestows a statue (I believe) of Khaine with a fraction of his power so that he may smite the enemies of the Eldar.
Do you mean Incubi? If you mean an entire cult, then you may be getting your WHFB and 40K lore mixed up again.Can't remember if this was canon or not but I think there's a dark Eldar cult dedicated to reuniting Khaine.