Which powerful god sent torrential rain that prompted Lord Krishna to lift Mount Govardhan?

Indra

Answer:  Indra
According to the narrative, the powerful god Indra sent the torrential rain that led Lord Krishna to lift Mount Govardhan.

Krishna Lifts Mount Govardhan from a dispersed Harivamsa Purana is attributed to Miskin (1585–90). It is in the collection of the Metropolitan Museum of Art, New York, USA. Harivamsa Purana is one of the many Sanskrit manuscripts, which were translated into Persian by the Mughals. This painting is on a theme from Harivamsa. Badauni, a scholar noble in the court of Akbar, was assigned the job of translating this volume on Lord Krishna into Persian. It is interesting to note that Badauni was famous for his orthodox religious views, much unlike Abul Fazl, another famous scholar chronicler in Akbar’s court. Hari or Lord Krishna lifted the mountain, Govardhan, with all creatures dwelling therein with the intention to protect them — the villagers and their livestock, who were his followers, from torrential rain sent by another powerful God Indra. Hari uses the mountain like a huge umbrella, under which the entire village takes refuge.