The word Shakti means divine feminine force, and Durga is the warrior aspect of the Divine Mother. Other incarnations include Annapurna and Karunamayi (karuna = kindness). Durga's darker aspect Kali is represented as the consort of the god Shiva, on whose body she is often seen standing.
As a goddess, Durga's feminine power contains the energies of the gods. Each of her weapons was gifted to her by various gods: Rudra's trident, Vishnu's discus, Indra's thunderbolt, Brahma's kamandalu, Kuber's Ratnahar, etc.
According to a narrative in the Devi Mahatmya story of the Markandeya Purana text, Durga was created as a warrior goddess to fight an asura (an inhumane force/demon) named Mahishasur. He had unleashed a reign of terror on earth, heaven and the nether worlds, and he could not be defeated by any man or god, anywhere. The gods went to Brahma, who had given Mahishasura the power to be the invincible conqueror of the universe. Brahma could do nothing. They made Brahma
their leader and went to Vaikuntha — the place where Vishnu lay on Ananta Naag. They found both Vishnu and Shiva, and Brahma eloquently related the reign of terror Mahishasur had unleashed on the three worlds. Hearing this Vishnu, Shiva and all of the gods became very angry and beams of fierce light emerged from their bodies. The blinding sea of light met at the Ashram of a priest named Katyan. The goddess Durga took the name Katyani from the priest and emerged from
the sea of light. She introduced herself in the language of the Rig-Veda, saying she was the form of the supreme Brahman who had created all the gods. Now she had come to fight the demon to save the gods. They did not create her; it was her lila that she emerged from their combined energy. The gods were blessed with her compassion.
It is said that upon initially encountering Durga, Mahishasura underestimated her, thinking: "How can a woman kill me, Mahishasur — the one who has defeated the trinity of gods?" However, Durga roared with laughter, which caused an earthquake which made Mahishasur aware of her powers.
And the terrible Mahishasur rampaged against her, changing forms many times. First he was a buffalo demon, and she defeated him with her sword. Then he changed forms and became an elephant that tied up the goddess's tiger and began to pull it towards him. The goddess cut off his trunk with her sword. The demon Mahishasur continued his terrorizing, taking the form of a lion, and then the form of a man, but both of them were gracefully slain by Durga.
Then Mahishasur began attacking once more, starting to take the form of a buffalo again. The patient goddess became very angry, and as she sipped divine wine from a cup she smiled and proclaimed to Mahishasur in a colorful tone — "Roar with delight while you still can, O illiterate demon, because when I will kill you after drinking this, the gods themselves will roar with delight". When Mahashaur had half emerged into his buffalo form, he was paralyzed by the extreme light emitting from the goddess's body. The goddess
then resounded with laughter before cutting Mahishasur's head down with her sword.
Thus Durga slew Mahishasur, thus is the power of the fierce compassion of Durga. Hence, Mata Durga is also known as Mahishasurmardhini — the slayer of Mahishasur. According to one legend, the goddess Durga created an army to fight against the forces of the demon-king Mahishasur, who was terrorizing Heaven and Earth. After ten days of fighting, Durga and her army defeated Mahishasur and killed him. As a reward for their service, Durga bestowed upon her army the
knowledge of jewelry-making. Ever since, the Sonara community has been involved in the jewelry profession.
The goddess as Mahisasuramardhini appears quite early in Indian art. The Archaeological Museum in Matura has several statues on display including a 6-armed Kushana period Mahisasuramardhini that depicts her pressing down the buffalo with her lower hands. A Nagar plaque from the first century BC - first century AD depicts a 4-armed Mahisamardhini accompanied by a lion. But it is in the Gupta period that we see the finest representations of Mahisasuramardhini (2-, 4-, 6-, and at Udayagiri, 12-armed). The spear and trident are her most common weapons. a Mamallapuram relief shows the goddess
with 8 arms riding her lion subduing a bufalo-faced demon (as contrasted with a buffalo demon); a variation also seen at Ellora. In later sculptures (post-seventh Century), sculptures show the goddess having decapitated the buffalo demon.