There are three main disciplines in it; “divyachar” for practitioners of satva-guna, “virachar” for practitioners of rajo-guna and “pashvachar” for practitioners of tamo-guna. The activities of unqualified practitioners of “Virachar” and specially “pashvachar” have badly damaged the image of tantra and have earned bad name for it.
Besides the tantric scriptures it has also been described in the Vedic Upanishads as the “science of Brahma” and there are several methods prescribed for its awakening. All the sciences described as “vidya sambhuti” in Ishavasya Upanishad, as “hemvati” in Ken, as “Aditi” in Katha, as “prana-vidya, para-vidya” in Prashna, as “OM-kara” in Mandukya, as “yoga-vidya” in Aitreya, as “bhargavi varuni” in Taittariya, as “udgeeth, prana, antaraditya, gayatri, shandilya, antaryami, dahar, madhu, samvarga, panchagni, vaishvanar sciences” in Chandogya and Brahadaranyaka, as “devatma shakti, savita” in Shvetashvatara and as “balaki vidya” in Kaushitaki Upanishad are different social and customary names and forms of the same divine energy.
The above is an excerpt from https://www.beezone.com/DevatmaShakti/IntroIndex.html
There was a picture of Param Pujya Vishnutirthji Maharaj. One of my favorite holy Guru
He still is very active in bestowing diksha / awakening. Although his body is not there his love and surrender to the divine is very active and very eagerly helps ALL those who are on the divine path
This is his photo
Bhavin