by Jamgön Kongtrul Lodrö Taye, one of Tibet's greatest Buddhist masters, is a shining jewel of Tibetan literature, presenting essential teachings from the entire spectrum of practice lineages that existed in Tibet. In its eighteen volumes, Kongtrul brings together some of the most important texts on key topics of Buddhist thought and practice while also authoring significant new sections of his own. This volume presents a selection of teachings and practices centered on the mahāsiddhas, Indian masters of tantric Buddhism, some of whom were of vital importance in transmitting the Vajrayāna teachings to Tibet. The mahāsiddha Mitrayogin, whose work forms the majority of this volume, visited Tibet in the late twelfth century. His ritual texts and instructions are translated from Tibetan, including sādhanas, empowerments, guru yogas, authorization rituals for protector deities, and detailed compositions on Mahāmudra practice, or resting in the nature of mind. In addition to instructions given by mahāsiddhas, this volume includes ritual practices to visualize them and transmit their blessings, including a devotional text composed by Jamgön Kongtrul himself. This translation, which may be engaged as a practice manual, preserves ancient teachings significant to the literature and history of world religions.