"The King of Kasi had one son whose name was Sudaksina. After observing the ritualistic funeral ceremonies, he took a vow that since Krsna was the enemy of his father, he would kill Krsna and in that way liquidate his debt to his father. Therefore, accompanied by a learned priest qualified to help him, he began to worship Mahadeva, Lord Siva. The lord of the kingdom of Kasi is Visvanatha (Lord Siva). The temple of Lord Visvanatha is still existing in Varanasi, and many thousands of pilgrims still gather daily in that temple. By the worship of Sudaksina, Lord Siva was very much pleased, and he wanted to give a benediction to his devotee. Sudaksina's purpose was to kill Krsna, and therefore he prayed for a specific power by which he could kill Him. Lord Siva advised that Sudaksina, assisted by the brahmanas, execute the ritualistic ceremony for killing one's enemy. This ceremony is also mentioned in some of the tantras. Lord Siva informed Sudaksina that if such a black ritualistic ceremony were performed properly, then the evil spirit named Daksinagni would appear to carry out any order given to him. He would have to be employed, however, to kill someone other than a qualified brahmana. In such a case he would be accompanied by Lord Siva's ghostly companions, and the desire of Sudaksina to kill his enemy would be fulfilled.
When Sudaksina was encouraged by Lord Siva in that way, he became assured that he would be able to kill Krsna. With a determined vow of austerity, he began to execute the black art of chanting mantras, assisted by the priests. After this, out of the fire came a great demoniac form, whose hair, beard and mustache were exactly the color of hot copper. This form was very big and fierce. As the demon arose from the fire, cinders of fire emanated from the sockets of his eyes. The giant fiery demon appeared still more fierce due to the movements of his eyebrows. He exhibited long sharp teeth and, sticking out his long tongue, licked both sides of his lips. He was naked, and he carried a big trident, which was blazing like fire. After appearing from the fire of sacrifice, he stood wielding the trident in his hand. Instigated by Sudaksina, the demon proceeded toward the capital city, Dvaraka, along with his many hundreds of ghostly companions, and it appeared that he was going to burn all outer space to ashes. The surface of the earth trembled because of his striking steps. When he entered the city of Dvaraka, all the residents panicked, just like animals at the time of a forest fire.
At that time Krsna was engaged in playing chess in the royal assembly council hall. All the residents of Dvaraka approached and addressed Him, "Dear Lord of the three worlds, there is a great fiery demon ready to burn the whole city of Dvaraka. Please save us." Thus, after approaching Lord Krsna, all the inhabitants of Dvaraka began to appeal to Him for protection from the fiery demon who had just appeared in Dvaraka to devastate the whole city.
Lord Krsna, who specifically protects His devotees, saw that the whole population of Dvaraka was most perturbed by the presence of the great fiery demon. He immediately began to smiled and assured them, "Don't worry. I shall give you all protection." The Supreme Personality of Godhead, Krsna, is all-pervading. He is within everyone's heart, and He is without also in the form of the cosmic manifestation. He could understand that the fiery demon was a creation of Lord Siva, and in order to vanquish him He took His Sudarsana cakra and ordered him to take the necessary steps. The Sudarsana cakra appeared with the effulgence of millions of suns, his temperature being as powerful as that of the fire created at the end of the cosmic manifestation. By his own effulgence, the Sudarsana cakra began to illuminate the entire universe, on the surface of the earth as well as in outer space. Then the Sudarsana cakra began to freeze the fiery demon created by Lord Siva. In this way the fiery demon was checked by the Sudarsana cakra of Lord Krsna, and being defeated in his attempt to devastate the city of Dvaraka, he turned back.
Having failed to set fire to Dvaraka, he went back to Varanasi, the kingdom of Kasiraja. As a result of his return, all the priests who had helped instruct the black art of mantras, along with their employer, Sudaksina were burned into ashes by the glaring effulgence of the fiery demon. According to the methods of black art mantras instructed in the tantras, if the mantra fails to kill the enemy, then, because it must kill someone, it kills the original creator. Sudaksina was the originator, and the priests assisted him; therefore all of them were burned to ashes. This is the way of the demons: the demons create something to kill God, but by the same weapon the demons themselves are killed.
Following just behind the fiery demon, the Sudarsana cakra also entered Varanasi. This city had been very opulent and great for a very long time. Even now, the city of Varanasi is opulent and famous, and it is one of the important cities of India. There were then many big palaces, assembly houses, marketplaces and gates, with very important large monuments by the palaces and gates. Lecturing platforms could be found at each and every crossing of the roads. There was a treasury house, and elephant heads, horse heads, chariots, granaries, and places for distribution of foodstuffs. The city of Varanasi had been filled with all these material opulences for a very long time, but because the King of Kasi and his son Sudaksina were against Lord Krsna, the visnu-cakra Sudarsana (the disc weapon of Lord Krsna) devastated the whole city by burning all these important places. This excursion was more ravaging than modern bombing. The Sudarsana cakra, having thus finished his duty, came back to his Lord Sri Krsna at Dvaraka.
This narration of the devastation of Varanasi by Krsna's disc weapon, the Sudarsana cakra, is transcendental and auspicious. Anyone who narrates this story or anyone who hears this story with faith and attention will be released from all reaction to sinful activities. This is the assurance of Sukadeva Gosvami, who narrated this story to Pariksit Maharaja."
Krsna Book, Chapter 66
Bhaktivedanta Book Trust. Excerpted from text and purport of HDG A.C. Bhaktivedanta Swami Srila Prabhupada.