Pumm-Ra is the first Thunderian guise that Mumm-Ra asked the Ancient Spirits of Evil to grant him in one of his many attempts to destroy the ThunderCats. In this form, Mumm-Ra tried to deceive the ThunderCats into thinking he too was a survivor of Thundera’s destruction. He went so far as to have Cheetara drugged and placed with him at a fake campsite to set the foundation of his deceit. When Cheetara revived, she listened to Pumm-Ra tell his tale and seemed convinced enough to introduce him to the other ThunderCats.
It was not long after the ThunderCats Council decided to give Pumm-Ra a trial living arrangement with them that he set about to sabotage their equipment, and re-program it to signal the waiting Mutants to attack. However, the ThunderCats ultimately regained control of their fortress and cornered the Puma of Thundera, only to find out that he was Mumm-Ra. The devil priest reverted back into his warrior form then teleported himself back to the Black Pyramid.