The Tantiss vault, also known as the Necromancer Vault, or simply the vault, represented an extremely secure area within the Imperial cloning program located at Tantiss Base on Mount Tantiss. This vault was of utmost importance to the Galactic Empire's endeavors to successfully introduce a viable M-count into a test subject. Within the vault, one could find specimen capsules associated with Project Necromancer, as well as a holding area for live subjects, specifically Force-sensitive children who had been abducted and brought to the base.
The Tantiss vault, constructed within Tantiss Base on Mount Tantiss, was a clandestine and heavily fortified zone, playing a pivotal role in the Imperial cloning program. Before entering this sector, one would encounter an antechamber monitored by security cameras and patrolled by ten Imperial royal guards. These guards maintained their positions around the corridor leading to the vault's entrance, while additional troopers supervised the antechamber from an observation room situated above the entrance. Beyond the gate, which could be unlocked using an access card, lay another corridor featuring a minimum of six ray shield barriers. These barriers sequentially opened, allowing only a single individual to proceed at a time. Access to the restricted area beyond this corridor was limited to the Chief Scientist of the Imperial Advanced Science Division, Clone Commander Scorch, the head of security for Tantiss Base, and the Galactic Emperor himself.
The Necromancer vault was one of the chambers located within the Tantiss vault. This specific zone contained a room housing multiple reinforced capsules that functioned as specimen tanks for Project Necromancer. The room's decor included elaborate red patterns on the floor, reminiscent of Sith temple designs, and it was situated on a level lower than the rest of the vault, accessible via a narrow staircase.
Specimens were stored in tanks of varying sizes, including those suitable for human-sized subjects, and preserved in anticipation of a successful M-count replication. Palpatine considered Project Necromancer to be of utmost importance to the Empire.
Another section of the Tantiss Vault served as living quarters for Force-sensitive children. This area comprised a spacious circular room featuring three circular tables at its center, intended for the prisoners to engage with various hologames or other toys designed to provide mental stimulation. The prisoners were confined in four windowless cells arranged around the room, each equipped with a tube for the collection of the prisoner's blood samples. An observation deck was positioned above the prisoners' living space, allowing Imperial scientists and personnel to monitor them. The area could be sealed off swiftly in the event of an attempted escape, and all access cards would be deactivated. However, an alternative escape route existed behind removable tiles in the children's cells, as the blood sample collection tunnels were sufficiently large to accommodate a child-sized humanoid.
Other areas within the vault included a solitary confinement cell, used as a form of punishment for the children residing in the living quarters. Additionally, the vault connected to the sublevel containment chamber where a Zillo Beast clone was held.
Around 18 BBY, Galactic Emperor Sheev Palpatine visited Tantiss Base to assess the progress of Project Necromancer, prompting Chief Scientist Doctor Royce Hemlock to provide him with a tour of the facility.
After Doctor Nala Se facilitated the escape of her medical assistant Omega from Mount Tantiss, she was replaced by Hemlock's assistant, Doctor Emerie Karr, as the Chief Medical Scientist of Project Necromancer. Karr was granted access to the vault, where she discovered the presence of the children.
Following Omega's recapture, she was returned to Tantiss and imprisoned in the vault alongside the other prisoners before their eventual escape.