Purana: Samudra Manthan

Indra, while riding on Airawat, came across Sage Durvasa who offered him a special garland. Indra accepted the garland, placing it on the trunk of Airavat. Airavat, threw the garland to the ground. This enraged sage Durvasa, who cursed Indra and all devas to be bereft of all strength, energy, and fortune

In battles that followed this incident, the Devas were defeated and Asuras and gained control of the universe. To restore lost glory,wealth and well-being Devas formed an alliance with Asuras to jointly churn the 'Kshirsagar' for the Elixir of immortality, wealth and boons. This episode in the Puranas is known as 'Samunda Manthan'

Mount Mandara was used as the churning rod; Vasuki, the king of serpents, became the churning rope. The gods and demons pulled back and forth on the snake's body alternately, causing the mountain to rotate, which in turn churned the ocean. Lord Narayan was in his Kurma (Tortoise) avatar to provide a support to Mt. Mandara on his back.

'Samunda Manthan' released a number boons. The forst to emanate however was the lethal poison Halahal. The poison was so powerful that it can destroy all of creation. Lord Shiva consumed the poison and held it in his throat. As a result the color of Shiva's throat turned blue giving him the name of 'Neelakanta' ('Neela' means blue and 'kantha' means throat). 

The verse that describes the subsequent products from the Samudra Manthan goes as follows: 'Lakshmeeh kaustubhapaarijaatakasuraadhantarischandramaah, Gaavah kaamaduhaa sureswaragajorambhadidevaanganaah, Ashwah saptamukhovisam haridhanuh sankhomrtam chaambudheh, Ratnaaneeha chaturdasa pratidinam kuryaatsadaa mangalam'. 

Which translates to a boons like Laxmi (God to wealth), Apsaras beautiful female spirits), 'Kamdhenu' (wish fulfilling Cow), Airavat (Indra's Elephant). Gems like Kasturbha and ever-green tree Parijat and many more boons

Finally, Dhanvantari (heavenly physician) emerged with a pot containing Amrita (Elixir of immortality). The Gods and Asuras started to fight over Amrit. Lord Vishnu, in the form Mohini, an enchanting damsel, distracted the Asuras and distributed Amrit among the Devas. Asura RahuKetu, disguised himself as a God-head and drank  a few  drops of Amrit. But before the nectar could pass his throat, Mohini/Vishnu cut off his head with her the 'Sudarshana Chakra'. However, as an effect of the Amrit RahuKetu did not die, rather his head and body lived as seperate entities. 

The 'Samudra Manthan' episode ends with the rejuvenated Devas defeating the asuras.