Story of Ashwasen
When Arjun burned down the Khandav forest, he was killing all the serpents. Ashwasen's mother perished trying to save her son. Ashwasen seeks revenge on Arjun for killing his mother.
During the Kurukshetr war, Ashwasen hid inside an arrow of Karn. Aiming at Arjun's head, Karn shot the arrow with Ashwasen at the tip of the arrow. But Bhagwan Sri Krishn saw this and used his strength to press down the chariot. The arrow missed its mark. It hit and destroyed Arjun's crown. Ashwasen then attacked Arjun but Arjun slayed him with six sharp arrows.