Anuttarayoga Tantra
Appearance
In the Gelug school of Tibetan Buddhism, the highest of the four classes of tantra, characterized by the symbolic use of sexual and wrathful energy to effect transformation and attain enlightenment. The four levels of tantra in the Gelug system are, in order of increasing sophistication complexity, and symbolic employment of energy are Kriya Tantra, Charya Tantra, Yoga Tantra and Highest Yoga Tantra or Anuttara Yoga Tantra.