Indra, the king of the Devatas, was once cursed by Durvasa Muni to be bereft of all strength, energy, and fortune. As a result of this curse Asuras (demons) led by king Bali, defeated Indra and took control of the universe.
Indra and other devas went to Lord Vishnu for help. Lord Vishnu advised them to treat asuras in a diplomatic manner. Devas formed an alliance with asuras to jointly churn the ocean for the nectar of immortality (amrita) and to share it among them. However, Lord Vishnu told Devas that he would arrange nectar only for them.
The churning of the ocean was an elaborate process. During the churning, many Divine objects and beings emerged from the ocean. At the end of this process, Lord Dhanvantari appeared from the ocean. He was carrying with him a pot filled with the divine nectar of immortality.
The asuras snatched the pot containing the nectar and started quarreling about which of them will drink the nectar first. Lord Vishnu didn't miss this opportunity to trick them. He appeared as Mohini, a beautiful woman who fascinated the demons, recovered the nectar from them, and distributed it only amongst the demigods. As soon as the demigods drank it, they were invigorated with energy and defeated the demons.
List of songs in "Sri Dhavatri Slokam":-
1. Maruthuvanai Nindra
3. Kovaiyil Kovil
4. Aarogiyam Thantharulum
5. Sree dhanvanthiri Gayathri
6. Sree Dhanvanthri Dhiyanam