In Hindu mythology

Hindu mythology

Hindu religious literature is the large body of traditional narratives related to Hinduism, notably as contained in Sanskrit literature, such as the Sanskrit epics and the Puranas. As such, it is a subset of Nepali and Indian culture...

, Rambha was an asura

Asura

-In Hinduism:In Hinduism, the Asuras constitute a group of power-seeking deities, sometimes considered sinful and materialistic. The Daityas and Danavas were combinedly known as Asuras. The Asura were opposed to the Devas. Both groups are children of Kasyapa...

.

Rambha and Karambha were the asur brothers, born as the descendants of Danu. When they were young, both decided to do penance to get special powers to establish the rule of Danavs in the universe.

Penance and boon

Rambha started penance standing inside burning fire to please Agni

Agni

Agni is a Hindu deity, one of the most important of the Vedic gods. He is the god of fire and the acceptor of sacrifices. The sacrifices made to Agni go to the deities because Agni is a messenger from and to the other gods...

 Dev, while Karambha stood inside water to please Varuna

Varuna

In Vedic religion, Varuna is a god of the sky, of water and of the celestial ocean, as well as a god of law and of the underworld...

 Dev. When Indra

Indra

' or is the King of the demi-gods or Devas and Lord of Heaven or Svargaloka in Hindu mythology. He is also the God of War, Storms, and Rainfall.Indra is one of the chief deities in the Rigveda...

 came to know about them, he decided to kill both the brothers. Firstly, he converted himself into crocodile and killed Karambha inside the water. But Agni Dev saved Rambha when Indra tried to kill him. Finally, Rambha got boon from Agni Dev that he would not be killed by any God, demon or human. Rambha became really powerful after getting boon. He started mass killing of humans and other living beings.

Birth of Mahishasura

Once, he saw a water buffalo and fell in love with her. So he converted himself into a water ox and started living with her. While buffalo was pregnant, an another male ox got attracted towards her. Rambha and that stranger ox had a long fight and finally Rambha got killed by ox. Later, that ox got killed by the soldiers of Rambha.
Buffalo gave birth to a demon Mahishasura

Mahishasura

In Hindu mythology, Mahishasura was an asura.Mahishasura's father Rambha was king of the asuras, and he once fell in love with a water buffalo ; Mahishasura was born out of this union...

. As he was born out of the union of a buffalo and converted ox, so he had ability to change between human and buffalo form at will.