Set Harth established a base on Nar Shadda which he used to explore the mysteries of the Sith artifact in secret. Little by little, the Dark Side energy that surrounded the artifact shifted to Set Harth plunging him further and further into the Dark Side. When he felt that he had learned all he could from this artifact, Set Harth set out to discover more relics that survived the Battle of Ruusan. His search eventually led him to a Hutt slaver, who happened to be simultaneously dealing with another Dark Jedi, a woman by the name of Bal Serinus. Angered at Harth's presence, Serinus attacked him and the two dueled throughout the Hutt slaver's palace. The battle left the two Dark Jedi so weak that the Hutt imprisoned both in his dark dungeon.

During their imprisonment, the two learned to communicate telepathically and Set Harth became very attached to Bal Serinus, promising to protect her from any harm. One day, however, Serinus cut off all contact with Set Harth without so much as an explanation. Subsequently, Set Harth's bond of attachment turned into abhorrence as Set Harth vowed his revenge. At some point, Set Harth escaped his imprisonment to continue his quest for knowledge of the Dark Side of the Force. The secrets Set Harth discovered during his journeys were secrets that very few others were aware of, and fewer still achieved.

Merging cloning technology with his knowledge of the Force, Set Harth managed to transfer his essence into cloned bodies of his former self for close to a millennia. Maintaining relationships with only the cloning techs, Set Harth would use a body for about thirty years before trading it in for a younger version. While Set Harth's existence eventually fell into legend with sightings falling into the category of urban myth, a cult-like following developed around the mystery of Set Harth, with avid collectors sharing Set Harth memorabilia and holovids of supposed Set Harth sightings. While the Jedi Order was content to publicly maintain that his existence was little more than myth, secretly they feared what Set Harth actually achieved - that through the Dark Side of the Force, Set Harth discovered a way to cheat death.