The preparations occurred in 1963 upon the request of President Sukarno, and shortly after, a massive volcanic eruption of Gunung Agung killed almost two thousand people. This highly religious and important ceremony was held again in the early months of 1979. Traditionally, the ceremony of Eka Dasa Rudra occurs every hundred years. There must be a balance in the world between the forces of good and evil, and when the balance favours the latter, the ceremony msut be performed.
When the ceremony of Eka Dasa Rudra occurs – its preparation and the entire ceremony – it is with the involvement of the entire population of Bali. Basically, the eleven demons [of which Rudra is the most powerful] must be transformed in order that they become less threatening to the world balance. This is why then the ceremonies duration is 11 weeks with the number of ceremonies totalling thirty in all.
The beginning of the Eka Dasa Rudra is spectacular. This involves the symbolic washing of the Gods images in the sea. The whole procession takes three days and in this time the images are carried to the sea. But it is the sacrificing of a buffalo [whose horns are covered in gold casings and adorned with other valuables] to the sea demons that to most westerners would seem cruel, but to the Balinese its not. A large heavy stone is tied around the neck of the buffalo as it is forced into the swirling ocean. There are various chants and prayers by pemangku and pedanda, and there are dance rituals performed. The main one being the war dance, ‘baris’.
With the conclusion of the initial sacrifice and accompanying rituals, virtually everybody in Bali [or most of them] travel to the mother temple at Besakih. Every path and road leading from all the villages in Bali are filled with lines of worshippers carrying offerings up to the main temple at Besakih. When all are gathered, then the climax of Eka Dasa Rudra begins – the ‘Taur’ sacrifices. These sacrifices involve the pedanda directing their prayers in all 11 directions of what is called ‘Balinese space’, according to ancient rituals written on lontar-palm scripts. Whilst these prayers are being directed, two dozen or so priests sacrifice many animals and birds in an effort to appease the demonic manifestation of Bali’s supreme-being, Rudra.
Naturally the ceremony of Eka Dasa Rudra is much more complicated and detailed than I have explained. But you have the basics of the ceremony. To write about the entirety of Eka Dasa Rudra, it would be numerous pages.