Who trained Lord Parshuram?

Who trained Lord Parshuram? Bhagwan Parshurama is one of the greatest warriors and teachers in Hinduism. He has taught warriors like Bhishma, Drona, Karna, Rukmi and Sarangadwaya and will be the future teacher of Kalki. It should be noted that Parshuram isn’t an ordinary warrior but an incarnation of Lord Vishnu and an immortal (Chiranjeevi). Parshuram killed Kartavirya Arjuna because he stole the Kamadhenu cow from his father, Jamdagni. Later when his father was killed by Kartavirya’s sons, he swore to wipe out the entire dynasty and killed the Kshatriyas 21 times filling 5 lakes with blood. Parshuram possessed many weapons including the Pinaka Dhanush, Brahmastra and the Sudarshan Chakra. He had worshipped Lord Shiva in his childhood who gave him a Parshu (axe) naming him Parshuram. Mahadev personally trained him at his abode Kailash and gave him many weapons. Once, the two engaged in a battle where seeing Parshurama’s valour, Shiva granted Parshuram the element of Rudramsha, making him immortal.