Durga Saptashati — Mahishasura Mardini Katha

In the ancient age, the demon Mahishasura performed severe austerities for thousands of years. Pleased by his tapas, Lord Brahma appeared and granted him a boon. Mahishasura asked: "Let no man or god be able to slay me." The boon was granted.

Armed with this invincibility, Mahishasura gathered a vast demonic army and launched a war against the gods. The devas fought valiantly but were overwhelmed. Heaven fell, the gods were driven to the earth, and Mahishasura seated himself on Indra's throne and ruled the three worlds with terror.

The defeated gods approached Lord Brahma, who led them to Lord Vishnu and Lord Shiva. The three greatest gods were filled with divine anger at the demons' cruelty. From the concentrated energy (tej) of all the gods, a blinding divine light emerged, taking the form of a magnificent Goddess — Durga, the Divine Mother.

The gods offered her their weapons — Shiva his trident, Vishnu his Sudarshana Chakra, Indra his thunderbolt, Agni his spear, Vayu his bow, Varuna his conch. Seated on a lion, Devi descended to the battlefield. Her roar shook the heavens and the demons trembled.

For nine days and nights, the battle raged. Mahishasura sent his greatest generals — Chikshura, Chamara, Karala — all were slain. He himself changed into many forms: a buffalo, a lion, a man, an elephant. Each form was destroyed by the Goddess.

On the tenth day, Mahishasura emerged from his buffalo form in the shape of a great warrior. Devi leapt upon him, pinned him with her foot, and drove her trident through his heart. He fell dead, and the gods rained flowers from heaven, singing her praises. This tenth day is celebrated as Vijaya Dashami — Dussehra — the day of divine victory over evil.