Mahākāla is a deity common to Hinduism and Tantric Buddhism
In Buddhism, Mahākāla is a fierce form of Vishnu. While in Hinduism, Mahākāla is a fierce manifestation of both Shiva and Vishnu (Narasimha), and is the consort of the goddess Mahākālī; he most prominently appears in the Kalikula sect of Shaktism.
Mahākāla also appears as a protector deity known as a dharmapala in Vajrayana, Chinese Esoteric, and Tibetan Buddhism and also in the Chàn and Shingon traditions. He is known as Dàhēitiān and Daaih'hāktīn (大黑天) in Mandarin and Cantonese, Daeheukcheon (대흑천) in Korean, Đại Hắc Thiên in Vietnamese, and Daikokuten (大黒天) in Japanese.
Mahākāla is a Sanskrit bahuvrihi of mahā "great" and kāla "time/death", which means "beyond time" or death.
Tibetan: ནག་པོ་ཆེན་པོ།, nak po chen po means "Great Black One". Tibetan: མགོན་པོ།, gön po "Protector" is also used to refer specifically to Mahla.ākā
According to Shaktisamgama Tantra, the spouse of Mahakali is extremely frightening. Mahakala has four arms, three eyes and is of the brilliance of 10 million black fires of dissolution, dwells in the midst of eight cremation grounds. He is adorned with eight skulls, seated on five corpses, holds a trident, a drum, a sword and a scythe in his hands. He is adorned with ashes from the cremation ground and surrounded by numbers of loudly shrieking vultures and jackals. At his side is his consort symbolized as Kālī. Both Mahakala and Kālī represent the ultimate destructive power of Brahman and they are not bounded by any rules or regulations. They have the power to dissolve even time and space into themselves and exist as Void at the dissolution of the universe. They are responsible for the dissolution of the universe at the end of Kalpa.
They are also responsible for annihilating great evils and great demons when other gods, Devas and even Trimurtis fail to do so. Mahakala and Kali annihilates men, women, children, animals, the world and the entire universe without mercy because they are Kala or Time in the personified form and Time is not bound by anything and Time does not show mercy, nor does it wait for anything or anyone.
In some parts of Odisha, Jharkhand and Dooars, (that is, in northern Bengal), wild elephants are worshiped as Mahakala.
Mahakala is typically black in color. Just as all colours are absorbed and dissolved into black, all names and forms are said to melt into those of Mahakala, symbolizing his all-embracing, comprehensive nature. Black can also represent the total absence of colour, and again in this case it signifies the nature of Mahakala as ultimate or absolute reality. This principle is known in Sanskrit as "nirguna", beyond all quality and form, and it is typified by both interpretations.
Mahayana Buddhism, and all schools of Tibetan Buddhism, rely on Mahakala as guardian deity. He is depicted in a number of variations, each with distinctly different qualities and aspects. He is also regarded as the emanation of different beings in different cases, namely Avalokiteśvara (Wylie: spyan ras gzigs) or Cakrasaṃvara (Wylie: ’khor lo bde mchog). Mahakala is almost always depicted with a crown of five skulls, which represent the transmutation of the five kleśās (negative afflictions) into the five wisdoms.
The most notable variation in Mahakala's manifestations and depictions is in the number of arms, but other details can vary as well. For instance, in some cases there are Mahakalas in white, with multiple heads, without genitals, standing on varying numbers of various things, holding various implements, with alternative adornments, and so on.
The Two Armed Forms
The two-armed "Black-Cloaked Mahakala" (Wylie: mgon po ber nag chen) is a protector of the Karma Kagyu school clad in the cloak of a māntrika "warlock". His imagery derives from terma of the Nyingma school and was adopted by the Karma Kagyu during the time of Karma Pakshi, 2nd Karmapa Lama. He is often depicted with his consort, Rangjung Gyalmo. He is often thought to be the primary protector, but he is in fact the main protector of the Karmapas specifically. Four-Armed Mahakala is technically the primary protector. Six-Armed Mahakala (Wylie: mgon po phyag drug pa) is also a common dharmapala in the Kagyu school.
Various Four-Armed Mahakalas (Skt. Chaturbhūjamahākāla, Wylie: mgon po phyag bzhi pa) are the primary protectors of the Karma Kagyu, Drikung Kagyu, Drukpa Lineage and the Nyingma of Tibetan Buddhism. A four-armed Mahakala is also found in the Nyingma school, although the primary protector of the Dzogchen (Skt: Mahasandhi) teachings is Ekajati.
Nyingshuk came from Khyungpo Nenjor, the founder of the Shangpa Kagyu, and spread to all the lineages (Sakya, Nyingma, and Gelug) and to the Kagyu lineages. There are also terma lineages of various forms of Six-Armed Mahakala. Nyinghsuk, though derived from the Shangpa, is not the major Shangpa one; it is in a dancing posture rather than upright, and is a very advanced Mahakala practice. The White Six-Armed Mahakala (Skt: Ṣadbhūjasītamahākāla; Wylie: mgon po yid bzhin nor bu) is popular among Mongolian Gelugpas.
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Thangka: Mahakala Bernakchen by Enlightenment at Dakini Art