Mumm-Rana, the Ever-Good is the polar opposite version of the evil Mumm-Ra, the Ever-Living. She resides in the White Pyramid and calls to the Ancient Spirits of Good. She also has the ability to transform from her mummified state to a much stronger warrior form.
Mumm-Rana is most likely the Universe's answer to Mumm-Ra's existence. She is similar to Mumm-Ra, but only to fight against the forces of evil. She is under the guidance and blessings of the Ancient Spirits of Good. As the Black Pyramid is Mumm-Ra's home base, the White Pyramid is Mumm-Rana's. She replenishes her powers within it by resting, in her mummified state, on an ornate, smoothed stone platform on a dais.
When she transforms from her mummified state to into her warrior form, Mumm-Rana chants, "Ancient Spirits of Goodness, transform this gentle form to Mumm-Rana, the Ever Good." In the episode Mumm-Rana's Belt, before her temple was damaged, Mumm-Rana began to transform by chanting- "Ancient Powers of Goodness....."
In her true form, she is shown to be very powerful, as she bested the mutants Queen Luna and Luna in battle with ease. She even defeated the ThunderCats, with very little effort, under Mumm-Ra's spell. However, she is not as powerful as Mumm-Ra, as was shown when he bested her in combat. Her powers, like those of Mumm-Ra, are also limited depending on the time she spends outside her pyramid.