Emperor's sanctuary

A temple on the moon Yavin 4 served as the final sanctuary of the Sith Emperor, hosting his injured spirit after the loss of his host body. The Emperor's agents were supposed to use a artifact in the nearby Temple of Sacrifice to consume all life on the moon and funnel it to the Emperor, thus restoring his strength, but the Imperial Guard were slaughtered by the Order of Revan, and Revan's attempt to use the artifact himself—hoping to restore the Emperor so that he could be permanently killed—failed due to the intervention of the allied Sith Empire and Galactic Republic. Determined to end the Emperor nonetheless, Revan fled to the Emperor's resting place, but was defeated in battle in the temple's courtyard. The Emperor, having fed off of the death and chaos sown by the ongoing battle against the Revanites, was able to regain his strength and departed the moon without taking a physical form.

Text and facts from the “Emperor's sanctuary” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.