For those who are interested in Tantic Buddhism, I strongly recommend The Psychology of Buddhist Tantra by Rob Preece , Becoming Vajrasattva, 2nd Edition: The Tantric Path of Purification and Introduction to Tantra : The Transformation of Desire by Lama Yeshe. I have put quotes from the two great Buddhist scholars down below.
Tantric aspect of Buddhism is very popular in the west. We hear about some Empowerment ceremony taking a place in our area every week. Tantric Buddhism promises fast track to Enlightenment. The Highest Yoga Tantra claims to contain methods by which one can reach Enlightenment in a single lifetime or even, as Lama Tsonkapa's case three short years.
In the times we want everything better and faster, Tantric Buddhism seems to be appropriate for all those who wish to achieve Enlightenment in this lifetime.
Unfortunately, there is a law of physics that deals with effort, pace of effort and time, applies here, To achieve the same goal in shorter time, one has to have higher horsepower which is the rate of application of effort. If one wishes to achieve Enlightenment faster, should be willing to put tremendous effort at a very high rate. As Trungpa Rinpoche had repeatedly taught, the teachings of the three vehicles , Hinayana, Mahayana and Vajrayana or Tantrayana, are to be followed in sequence. One cannot jump to Vajrayana bypassing the teachings and realization of the preceding vehicles.
In other words, if you are ready to be on the path of Tantric Buddhism, that implies that you practice very high level of altruism, you have very high level of compassion for all sentient beings, you never get angry, you have mastered the entire text of the three baskets.
In the following text, the editor of the book Becoming Vajrasattva, 2nd Edition: The Tantric Path of Purification lays down the pre-requisites of starting on the Tantric Path.
"Before Lama Yeshe first began giving tantric initiations and teachings to his Western students, he made sure that they were well versed in the three principal aspects of the sutra path-- renunciation of cyclic existence, the altruistic attitude of bodhicitta, and the right view of emptiness (shunyata). Only after a period of dedicted study and meditation of sutra teaching did Lama Yeshe agreed to initiate them into the purification practice of Heruka Vajrasattva. Lama recognized that a solid grounding in the fundamentals of the Buddha's teachings on the nature of suffering and liberation is essential to gaining any benefit from the practice of Tantra".
In the following text from The Psychology of Buddhist Tantra, Rob Preece clarifies that deity in Tantra is an aspect of the consciousness of the practitioner.
"The deity in Tantra can be understood as a gateway or bridge between two aspects of reality. Buddhism has no concept of a creator God, as do theistic religions. The deity is not be viewed as a god in the sense of an entity that has an autonomous existence beyond human consciousness. Rather, the deity is a symbolic aspect of forces that arise on a threshold between two dimensions of reality, or two dimensions of awareness."