Complex sentence: Sagar Manthan was performed with the help of Sri Vishnu himself, where he empowered the devas and the asuras, as well as the great serpent Vasuki, and also held the great mountain used to churn the ocean.
Split into simpler sentences: Sagar Manthan was performed with the help of Sri Vishnu himself. Vishnu empowered the Gods and Demons, as well as the great Snake Vasuki, and also held the great mountain used to churn the ocean.