Buddha Akshobhya (Tib: Mitrugpa)
Buddha Akshobhya -> Vajrapani -> Indian Mahasiddhas including Aryadeva -> Palden Atisha brought into Tibet -> after number of Lineage Holders -> Tsangpa Gyare -> -> -> Drukpa Choegon & Drukpa Yongzin Rinpoches about 500 years ago.
Drukpa Kagyu's Lineage holds the main lineage of Buddha Akshobhya, mainly in Dechen Choekhor (the seat of Drukpa Choegon & Drukpa Yongzin Rinpoches), Khampagar (the seat of Khamtrul Rinpoche) and Nangchen Garh (the seat of Adeu Rinpoche) and all their lineage holders. This lineage is directly from Buddha Akshobhya, Vajrapani, Arya Deva, down to Atisha who travel to Tibet, and then, from Tsangpa Gyare to Choegon Rinpoche's Lineages of Dechen Choekhor tradition. From there, the practice of Akshobhya Buddha has spread to most Drukpa Kagyu monasteries in 16th century.
Dechen Choekhor put particular emphasis in Buddha Akshobhya practices. It has been their exclusive and intensive practices for puja, Jangchok, retreat, purification and other rituals. This blessings lineage was kept intact unbroken through their perseverance and diligent practices, particularly the Choegon Rinpoche Lineage, for over 500 years. The Akshobhya Buddha practice is still a mandatory retreat practices in Dechen Choekhor's tradition till today. It's regarded as one of the Four Main Essential Practices of Drukpa Kargyu.
Buddha Akshobhya, the 'Unshakeable One', Lord of the Vajra Family, is one of the Five Dhyani Buddhas or Five Wisdom Buddhas (Skt: Dhyani for "Meditation"); representing the fully purified skandha, or aggregates of form.
Buddha Akshobhya established the enlightened intention that all sentient beings could purify any degree of non-virtue, even the extreme non-virtue of hatred, violence, and killing can be cleansed through relying on him as the focus of meditation, acknowledging and abandoning non-virtuous actions, and invoking his blessings of purification.
In the Akshobhya's Sutra, Buddha Sakyamuni himself extolled the perseverance of Akshobhya in actualizing this intention so powerfully that countless beings have been saved from the intense suffering of lower states of existence.
Buddha Akshobhya, the immutable and imperturbable, is associated with the east and represents the vajra family. He is blue in coloured, sits on a lotus throne supported by the elephant, symbolizes steadfastness and strength; his right hand making the bhumisparsha mudra, the earth-touching gesture, denotes unshakability; while his left hand rests on his lap holding a vajra. Vajra denotes enlighten mind, the indestructible, adamantine nature of pure consciousness, or the essence of ultimate reality.
According to the Buddhist teachings, the present age is one of degeneration when all beings in the cycle of existence (samsara) are suffering in great deal because of their negative actions and disturbing emotions.
Akshobhya explicitly promised that the merit generated by reciting 100,000 of his long dharani mantra and creating an image of him could be dedicated to others, even someone long deceased, and they would be assured of release from lower states of existence, and take rebirth in spiritually fortunate circumstances.
Meditation on Akshobhya is best for cleansing karma related to negative actions. Through the power of this practice of ritual purity and lustration, the force of negative karma is weakened, and only then one can progress steadily in their path to enlightenment.