The Story of Banasur

The demon devotee who ignited a war between Shiva and Krishna
Who was Banasur?
Banasura was the son of Bali and great grandson of Bhakta Prahlada. He ruled over the city of Shonitapura. He was terribly powerful and a great devotee of Shiva. He pleased Shiva by playing musical instruments by his thousand arms during Shiva's Tandav dance and received a blessing that Shiva himself would guard and protect Shonitpura, his city.
Due to his own strength and power and now also because of Shiva's protection he became invincible in the entire world.
The Strange Dream
Banasur had a beautiful daughter Usha. One day she had an erotic dream in which she saw a young man who made love to her and married her. Usha confided in her friend Chitralekha about the dream who drew a sketch of the man according to verbal description given by Usha. When the sketch was ready Chitralekha recognised him to be Krishna's grandson Aniruddha.
Chitralekha went to Dwaraka and using her Maya powers and brought Aniruddha with her to Shonitapura. Aniruddha and Usha quickly fell in love. Anirudha stayed hidden in her rooms so no one saw him.
The Capture
Bana's gaurds noticed Usha's strange behaviour that seemed to signal as if she was married. They reported it to Banasur who became very angry and sent army after army to capture Aniruddha but Aniruddha defeated them all easily. Finally Bana himself came down to fight him. Despite a long battle, Bana was unable to overpower Aniruddha. Finally Bana used Maya to become invisible and used Nagapashas to capture Aniruddha and imprisoned him.
Krishna attacks Banasura
A month had passed since his capture. Meanwhile everyone was worried about missing Anirudddha at Dwarka. When Narada arrived in Dwaraka and informed everyone about Aniruddha's abduction and capture in Shonitapura, Krishna immediately summoned Garuda and along with Pradyumna and Balarama left to save his grandson.
A fierce battle ensued between Krishna and Shiva. When Shiva couldn't win Krishna he introduce 'Shiva fever' which started burning everyone, even attacked Balaram and overwhelmed him. Then the fever tried to attack Krishna. But Krishna created a Vaishnava Fever from his body that overpowered the Shiva fever. Brahma begged Krishna to spare the Shiva fever. Krishna honouring his request recalled the Vaishnava fever back into his body and spared the Shiva fever.
Battle between Krishna and Shiva
Krishna fought Shiva fiercely and defeated Banasur in the end and cut off all of his thousand arms. Then Lord Shiva requested Krishna to spare Bana's life. Krishna smiled and revealed that he never intended to kill Bana. As Narasimha, he had given a boon to prahlada that he won't slay any of his descendants. He was simply toying with Banasur to vanquish his pride
Bana was ashamed of his wicked deeds. Krishna went towards Aniruddha. On seeing Garuda, the snakes surrounding Aniruddha fled in terror. Along with Aniruddha and his new wife, Krishna returned to Dwaraka victorious.
