Śivasaṃhitā 5.203

The rājādhirāja yoga (the supreme yoga among all royal yogas) is presented as the most guarded secret of all tantras. It is not a specific text but the understanding that traverses and unifies all tantric systems under different names and forms. Śiva claims to have described it here—pointing to the Śiva-saṃhitā as bearing the heart of the complete tantric tradition.

Rāja-adhirāja = king of kings, the supreme among sovereigns, ākhyāta = described/proclaimed (ā-khyā = to declare), sarva-tantra = all tantras (all teachings/systems), gopita = hidden/guarded. The eighteen lacs produce utkrānti (elevation of the body from earth) and divya-deha (divine/luminous body).

The divya-deha as a result of eighteen million mantra repetitions connects this text with the external alchemy (rasāyana) of the Nāthas: both systems seek to transform the ordinary body into an indestructible vehicle of pure consciousness. Levitation (utkrānti) is the visible sign of the vajra-deha: the body no longer subject to karma’s gravity.