This episode is from [Devi:5.2.1-5.18-70], which tells the detailed story of how the Goddess Durga slew the buffalo-demon Mahishasura.
Long ago, an Asura named Rambha was the king of the Asuras. While walking through the streets, he saw a beautiful she-buffalo and was immediately smitten with desire for her. The union of Rambha and the buffalo produced a son named Mahishasura. Upon Rambha’s death, Mahishasura became the king of the Asuras.
Mahishasura, like many Asuras before him, desired to conquer the Devas (gods), their eternal rivals. Knowing the strength of the Devas, Mahishasura undertook a severe penance directed toward Lord Brahma, the creator of all creatures, in order to gain strength and protection.
After a long period of penance, Lord Brahma appeared before Mahishasura and asked, “Child, your prayers have pleased me. Ask of me what your heart desires.”
Mahishasura replied, “Lord, let me become immortal. May I have naught to fear from death!”
Brahma, smiling gently, responded, “Immortality is not possible, as all creation must come to an end. Immortality is beyond even my power to grant. Anything else, however, I shall bestow upon you.”
Mahishasura then asked, “If I cannot be immortal, then grant me that I may not die at the hands of any man, Deva, or member of the Trinity (Brahma, Vishnu, Shiva). If I must die, may it be at the hands of a woman, for women are weak and powerless. How could a woman possibly kill me, Mahishasura, the mighty Asura?”
Brahma granted him this boon, saying, “Your wish is granted, but know that death shall indeed come to you, and it will be through a woman, as fate decrees.” With this, Brahma disappeared.
With this boon, Mahishasura believed himself invincible. He began amassing a great army led by his trusted general Sikshura. His army included other powerful Asuras such as Asiloma, Utharaka, Bidala, Bashkala, Trinetra, and Kalabandhaka. This army embarked on a campaign of conquest, subjugating kingdoms and expanding Mahishasura’s domain. Soon, Mahishasura became the ruler of the entire earth.
After establishing his rule on earth, Mahishasura set his sights on the heavens. Addressing his generals, he said, “We have conquered the earth, and now it is time to claim our rightful place in Amravati, the realm of the Devas. We have long been banished to the underworld, while the Devas enjoy the pleasures of heaven. It is time to avenge this injustice. Lord Brahma has guaranteed our victory. Prepare the army, for at dawn, we march on the Devas’ capital.”
The next day, Mahishasura performed a great Yagna (sacrifice) and sought the blessings of his guru, Shukra. His army, confident in their king’s invulnerability, marched toward heaven.
When Indra, the king of the Devas, heard of Mahishasura’s advance, he summoned his council of Devas, including Yama, Vayu, Varuna, and Agni. “Mahishasura has declared war on us. He offers us two choices—surrender and serve him, or meet him in battle. What say you?”
The Devas unanimously opted for battle, but they needed the guidance of their Guru, Brihaspati. Upon his arrival, Brihaspati said, “Victory is not guaranteed by strength or intellect but by the favor of the Gods. Go to Lord Brahma and seek his assistance.”
The Devas went to Brahma-loka, and Brahma, aware of Mahishasura’s boon, said, “I cannot harm him. His death lies in the hands of a woman. Let us seek the help of Shiva and Vishnu.”
The Devas, along with Brahma, approached Shiva on Kailasa and explained their plight. Shiva, realizing the gravity of the situation, suggested that they all go to Vaikunta to seek Vishnu’s advice.
In the ensuing battle between the Devas and Asuras, Mahishasura unleashed his full might, shifting between forms—a lion, a man, and finally a mighty buffalo. Despite the combined efforts of Brahma, Vishnu, and Shiva, the Devas were unable to defeat Mahishasura due to his boon. In desperation, they retreated from the battlefield.
The Devas, having fled from heaven, wandered aimlessly until they gathered again to seek Brahma’s counsel. Brahma reminded them that Mahishasura could only be defeated by a woman. This sparked the idea to create a powerful Goddess from the combined energy of all the Devas.
From the combined energy of Brahma, Vishnu, Shiva, and the other Devas, a radiant and powerful woman was born—Mahalakshmi, also known as Durga. She was three-eyed, with eighteen arms, and her beauty and strength were beyond comprehension. Each of her body parts was created by the energy of different Devas—her face from Shiva, her arms from Vishnu, her eyes from Agni, and so on.
Each of the Devas gave her their most powerful weapons—Vishnu gave her a discus, Shiva gave her a trident, Indra gave her his Vajra, and Varuna bestowed upon her a noose. Armed with these divine weapons, Durga mounted her lion and let out a mighty roar that echoed across the heavens.
Mahishasura, hearing this roar, sent his armies to investigate. When his soldiers saw Durga, they were terrified and fled. The Asura king, struck by her beauty, desired her for himself and sent his ministers to woo her. Durga, laughing at their audacity, challenged Mahishasura to a battle.
The battle that followed was fierce. Durga, with her lion, fought Mahishasura’s generals, slaying them one by one. The lion tore through the Asura ranks, and the Goddess herself killed the mightiest warriors, including Bashkala, Durmukha, Sikshura, and Tamra.
Finally, Mahishasura himself took the battlefield, shifting between his forms as a man, a lion, an elephant, and a buffalo. Durga met each of his transformations with ferocity. As Mahishasura, in his buffalo form, charged at the Goddess, she struck him with her trident and beheaded him with her discus.
Thus, Mahishasura, who had terrorized the heavens and believed himself invincible, was slain by the divine force of Durga, the warrior goddess born of the combined power of the Devas. With his death, the Devas regained their heavenly abode, and Durga was hailed as the savior of the Gods and the universe.
This story from the Devi Mahatmya emphasizes the theme that the balance between good and evil is restored by divine intervention, with the Goddess Durga symbolizing the power of righteousness and the ultimate protector of the universe.