The Py'tar was the life force of the planet Kalanor. A self-sustaining nuclear reaction, the Py'tar made Kalanor a paradise. But it was somehow suppressed, and Kalanor was reduced to a desert world.
When Despero was banished from the city and set upon by robbers, the Py'tar cracked open the valley he was in and destroyed his assailants. It spoke to Despero through his third eye, telling him that it could make Kalanor a paradise again, and that he was to make it so. But Despero had been hardened by his years of abuse and ridicule, and in his anger used the Py'tar to conquer Kalanor, then hoped to conquer the galaxy.
Not understanding what it was, the Justice League and the Green Lantern Corps decided to destroy the Py'tar with a carbon bomb. However, J'onn J'onzz was able to sense the Py'tar's mind, and threw himself into the flame, becoming possessed by the Py'tar. Using J'onn as a conduit, the Py'tar offered to make Kalanor a paradise once more, but only if the Kalanorians rejected Despero and his madness. The Kalanorians accepted, and Py'tar reemerged from its hibernation, bringing a thriving ecosystem to Kalanor. The soldiers empowered by the Py'tar were turned into trees, and an enlightened Despero was swallowed by a great plant.