The Churning Rope

The Bhagavata Purana and the Vishnu Purana both tell the churning of the ocean of milk as the episode that gives Vasuki his central place in Hindu myth. With the devas weakened by a sage's curse and unable to hold the asuras off unaided, the two sides agree to a temporary truce and cooperate to churn the cosmic ocean for amrita, using Mount Mandara as the churning rod and Vasuki, king of the nagas, wound around it as the rope.

The asuras take hold at Vasuki's head end and the devas at his tail, and the mountain, resting on the back of Vishnu in his tortoise incarnation Kurma to keep it from sinking, is spun back and forth to churn the ocean. The friction and effort of the churning cause Vasuki to vomit a virulent poison, halahala, threatening to destroy all of creation before Shiva swallows it and holds it in his throat, turning the skin there blue permanently and giving him the epithet Nilakantha, the blue throated one. Vasuki survives the entire ordeal, and the amrita and various other treasures emerge from the ocean only after the churning is complete, setting up the conflict over who gets to keep the elixir that follows.