After a Third Earth era sealed in a tomb, Grune's unsettled spirit was released onto the countryside. It wasn't until after a sadistic introduction to the Thundercats did Grune again confront Jaga and was defeated.

It wasn't the last battle between the two rival spirits. In the rescue of Pumyra, Ben-Gali and Lynx-O from Fire Rock Mountain, Jaga traveled across time and space to ask for the power of the Star of Thundera. Jaga was confronted once more by Grune. It would be the Star of Thundera itself that would save Jaga from a nearby Astral black hole and hurl Grune into it instead.

Grune made a final appearance in another attempt to exact his revenge on his former people. Mumm-Ra brought the spirit of Grune back from the endless pit of lost souls to engage the Thundercats once more, and he was defeated.