The oracle stone was an ancient Sith artifact that could be used to aid a user's clairvoyance. The powers granted by the oracle stone could be detected and countered by a Jedi using battle meditation, however.
During his pilgrimage to the planet Korriban, the reborn Emperor Palpatine used it to locate Anakin Solo so that he might be able to use the young child's body to prolong his existence. Lumiya also possessed the Oracle stone and used it to monitor events occurring across the galaxy.
- Evil Never Dies: The Sith Dynasties on Hyperspace
- The Complete Star Wars Encyclopedia