Durga and Mahishasura
दुर्गा
Mahishasura was a terrible demon who performed intense penance and received a boon from Lord Brahma that no god or man could kill him. Empowered by this boon, he attacked heaven and defeated all the gods. The frightened gods went to Lord Vishnu and Shiva for help. Then the combined energies of all the gods merged to create a supreme divine feminine power — Goddess Durga. Shiva gave his trident, Vishnu his discus, Indra his thunderbolt, and every god contributed a weapon. The Himalayas gave a lion as her mount. Goddess Durga manifested with ten arms, radiating brilliant divine light. A fierce battle raged between Goddess Durga and Mahishasura for nine days. The demon kept changing forms — becoming a buffalo, then a lion, then an elephant. But Goddess Durga defeated every form he took. On the tenth day, she pierced Mahishasura with her trident and destroyed him. The festivals of Navratri and Dussehra are celebrated to commemorate this glorious victory of good over evil.
Moral
No matter how powerful evil grows, it can be defeated with strength and courage.