X-70B Phantoms were so technologically advanced they were never mass-produced. Instead they were elite vessels bestowed upon only the most trusted intelligence agents for the most vital missions to the Empire during the Great Galactic War. The ships were coated with a sensor-resistant exterior and equipped with the most sophisticated equipment and weapons.
Exal Kressh, Sith apprentice to the Sith Emperor, piloted an X-70B prototype when she defected from the Emperor's service. She first traveled in her ship to an unidentified planet in the Peragus system, before she was pursued by a fellow Sith apprentice, Teneb Kel. She then used it to escape from the destroyed Lenico Colony Blue and return to Korriban in the Horuset system shortly before the Republic attack on Korriban.
Another of these ships would be given to be used as the personal ship of an Imperial Agent named Cipher Nine in order to travel across the galaxy on various operations from transport to space battles.
Darth Serevin used X-70B during the Battle of Ilum where he to oversaw Darth Malgus's New Empire forces. His ship was captured during the battle and used to deliver a strike force to Malgus' space station, which eliminated the false emperor.