This artifact stands in the middle of the Vector crossover.
Karness Muur lived around 7000 BBY. He lived during the 100-year darkness. He was a Sith, who pre-dated the creation of the Sith Order. It is rumoured that he may have been a contemporary of Xoxaan( the Sith Lord who guided Darth Krayt in the Dark Side of the Force).
Like many Dark siders of his time, Karness Muur used the power of the Force to twist life itself into monstrous creations. Rumours say that he had a hand in the creation of the Leviathans. He along with other Dark siders, made a last stand against the Jedi Hunters on the planet Corbos. This battle ended the 100-year Darkness. Muur fled.
The surviving Dark Siders fled to Korriban. There the native Sith welcomed them as Gods. Muur sought to defy death. He created the Talisman, into which he invested his very mind and will to preserve his essence.
Since Muur's death, the Talisman had sought out powerful Force users, so that Karness Muur would have access to the Force through them. The Talis man had managed to hide itself from the Force for a very long time.
Then one day, the Talisman was found by a Jedi, Celeste Morne, who sought to wear it, to prevent Muur from locating other hosts. She drew power from the Talisman, which kept her alive for thousands of years. During the Vector saga, Celeste saw the true selfless nature of Cade Skywalker, and surrendered herself. After Morne's death, the Talisman found itself joined to Cade, but only momentarily. Cade saw through the imperfections in its design and destroyed it using the Force. With that, the essence of Karness Muur, too, was gone.