Yamantaka (gShin-rje gshed, gShin-rje mthar-byed) is specifically the type of practice that is done to overcome death. Yamantaka: Yama is “death,” the “Lord of Death,” and antaka, “the one who puts an end to,” so “the one who puts an end to the Lord of Death.” Yamantaka is in the form of a very, very strong, forceful figure and has Manjushri in his heart (so very peaceful, calm, the complete understanding of reality). This is, just in very general terms, a little bit of what is Yamantaka all about for those who might not have so much of a background.
In the Gelug tradition this became very, very strongly practiced. In this system of putting together the three practices of these three deity systems – Guhyasamaja, Chakrasamvara, and Yamantaka or Vajrabhairava (two names) – Yamantaka is the container within which the other two practices can be included. And all the protector practices that are done in the Gelug tradition are all done within the context of oneself arising as Yamantaka.
Yamantaka practice became especially popular and widespread not only among the Tibetans, but also in the Mongol and Manchu regions in which Tibetan Buddhism spread.