The Custom of such guhya or secretive Bhairava is undoubtedly an oral tradition that is continuous in the guru disciple tradition. Their karmakand rituals and tactics are mystery, they aren't written down but only learnt and practiced in Expert disciple tradition. Of the numerous avatars of Lord Shiva, Kaal Bhairav https://www.youtube.com/shorts/0vLISs2kzMI