Deity yoga is the meditative practice of imagining oneself as an ideal being, fully endowed with compassion, wisdom, and their resultant altruistic activities. The idea is that by imagining being a Buddha one gets closer to actually achieving Buddhahood. Tantric Techniques offers a complete system of Tantric meditation comparing the views of three seminal Tibetan authors on deity yoga and on issues such as how to safeguard against psychological inflation and how to use negative emotions on the path.
Paul Jeffrey Hopkins, Ph.D. (Buddhist Studies, University of Wisconsin-Madison, 1973; B.A. English Literature, Harvard University, 1963), served for a decade as the chief English-language interpreter for the Dalai Lama. A Buddhist scholar and the author of more than thirty-five books, he is Professor Emeritus at the University of Virginia, where he founded the largest academic program in Tibetan Buddhist studies in the West.
While Hopkins' writing style is somewhat dry and academic, there is still useful information here that Vajrayana Tantric practitioners can use. Sometimes an objective, detached analysis of meditation and its intended cultivated mind states can teach us just as much as a book written by a teacher! There is a lot of comparing and contrasting the opinions on Tantra held by past Buddhist masters like Tsongkhapa, Longchenpa, Buton Rinchen Drup, etc., and it is in those chapters that the text gets bogged down and becomes difficult to get through. The book is almost completely concerned with discussing the generation stage meditations (which Hopkins calls development stage) of Tantra; there is very, very little on completion stage practices in this book. The book relies heavily on Gelugpa sources and obviously is written more from that perspective. As a Gelugpa myself, I have no issues with this, but those who practice in other Tibetan Buddhist traditions might find it a bit lacking.