The moniker "Curse of Graush" described the physical and psychological transformations undergone by an individual inhabited by the spirit of Dathka Graush. Prior to 7000 BBY, the Sith King Dathka Graush had his biological heart substituted with a dark side Force-sensitive crystal through the utilization of Sith magic combined with cutting edge technology. Following Graush's death by assassination, the crystal was interred with his body within his tomb situated in Korriban's Valley of Golg.
Precisely a half year prior to the Battle of Yavin, Naz Felyood, the captain of a pirate freighter, inadvertently triggered Graush's crystalline heart, resulting in a fleeting possession by the spirit of Graush. This event halted Felyood's natural aging process. Felyood's regenerative capabilities also increased tenfold compared to a typical being, and he developed a significant resilience against physical harm from energy weapons, vibroweapons, and the majority of close-quarters combat implements. Additionally, the lingering dark side energies granted Felyood the capacity to communicate, comprehend, and transcribe the ancient Sith language.