How it is told
Who was Bhima, the demon at Bhimashankar?
Born after the war
Kumbhakarna was killed by Rama at Lanka. His wife Karkati was carrying their son and went away into the Sahyadri hills to raise him, and told him nothing — not his father's name, not the war, not who had ended it.
The question, and the answer
He asked eventually, the way children do, and she told him all of it: Lanka, Rama, his father asleep and then dead. The story turns on this moment. Everything Bhima does afterwards is a man avenging someone he never met, on people who had nothing to do with it.
A thousand years of preparation
He did penance to Brahma for a thousand years and was given strength no one could stand against. Then he went and took Kamarupa, and imprisoned its king, Kamarupeshwar, whose only offence was devotion to Shiva — the god he had decided was on the other side.
The order nobody could obey
Bhima ordered that he be worshipped in Shiva's place. In the cell, the king made a lingam out of the earth of the floor and went on with his own worship, as he had every day of his life.
The sword that came down on a lump of clay
Told about it, Bhima went down to the cell and swung at the lingam himself. He did not reach it. Shiva came out of it, and the fight that followed is the one the shrine is named for — not the demon's defeat but the moment the two of them actually met.
What the battle left
Bhima was reduced to ash. The gods asked Shiva to stay, and he stayed as Bhimashankar. The sweat of the fight is said to have run off the hill and become the Bhima river, which does rise here and does run three hundred kilometres east to the Krishna.