In VAMANA Avatar, Lord Vishnu embodies himself as a bantam minister in this world. Bali, the grandson of Prahlada was an exceptionally valorous and strong asura. By his retribution and might, he vanquished the entire world. Indra and different divine beings expecting that he and asuras would overcome all the three universes, went to Lord Vishnu for help. 

Master Vishnu was then conceived as a diminutive person Vamana in the family of a brahmana (minister). He went to Bali on growing up and requested charity. Bali was pleased to offer him anything he mentioned despite the fact that his minister cautioned him that it was Lord Vishnu. 

Vamana then mentioned for the measure of land that could go under his three feet. Bali nimbly concurred. Ruler Vishnu at that point developed in size and secured the earth and paradise in two step.

 What's more, because of absence of room, he put his third leg on Bali himself and squashed Bali to the under or the Patala loka(underground world), in this way getting the Gods out.