Amitayus, or "Immeasurable Life," is a deity associated with longevity. In particular, Red Amitayus is the dharmakaya Buddha for theTukdrub Barché Künselmandala. This mandala is associated with Zangdok Palri, Guru Rinpoche’s pure realm, the Glorious Copper Coloured Mountain.
The palace in Zangdok Palri has three levels, the top level contains the head of the mandala, dharmakaya Amitayus. The second level contains sambhogakaya Ngensong Dongtruk (a form of Avalokiteshvara), and the ground level contains nirmanakaya Padmasambhava, alongside the twelve emanations of Guru Rinpoche. As Zangdok Palri is a sambhogakaya pure realm, dharmakaya Amitayus, the head of the pure realm is depicted in sambhogakaya attire. He is holding a vase containing amrita, the nectar of immortality, as well as the leaves of the ashoka tree, which confers longevity and freedom from disease. The practice of Amitayus eliminates obstacles to long life such as disease, pain, and accidents. The dharmakaya Amitayus is the first practice that Guru Rinpoche bestowed on his students as part of theTukdrub Barché Künsel.
In The Life-Story of the Master of Uḍḍiyāna, revealed by Chokgyur Dechen Lingpa, Guru Rinpoche confers his vision of Amitayus:
When I went to accomplish immortality in Māratika, Amitāyus, the protector, appeared before my eyes, And bestowed upon me one hundred and eight sādhanās on longevity. I then proceeded to the densely-arrayed buddhafield of Akaniṣṭa, And to the pure realms of the five buddha families. There I requested tantras from all the sugatas And I conversed with all the nirmāṇakāya buddhas, who declared: “Apart from this, your mind, there is no other buddha.”