The Sphere of Mysteries, alternatively referred to as the Ministry of Mysteries or the Pyramid of Mysteries, functioned as one of the twelve Spheres of Influence within the re-established Sith Empire. In an official capacity, this Sphere held the duty of safeguarding Imperial classified information and perilous knowledge that was not intended for dissemination. Adherents, including figures like Lord Anathemos, would meticulously search the galaxy for holocrons and other forms of confidential information, with the intent of securing them. Furthermore, the Sphere operated in secrecy, overseeing assassins and orchestrating the elimination of individuals deemed as significant threats to the Empire. A member of the Dark Council, specifically one of the twelve, was in command of this Sphere, marking it as the sole Sphere under the complete authority of its Sith overseer.
During the period known as the Cold War, Darth Rictus held the position of leader within the Sphere. The clandestine, and frequently violent, nature of the Sphere's operations led the elite circles of Imperial society to give it the moniker Assassin's Pyramid. Among all the Spheres of Influence, the Sphere of Mysteries was characterized by its extreme secrecy and covert operations. Consequently, the majority of Imperial citizens remained ignorant of the Sphere's actual functions and responsibilities.
Following the Empire's subjugation by the Eternal Empire, this particular sphere underwent a merger with the Spheres of Ancient Knowledge and Sith Philosophy, resulting in the formation of the Sphere of Sith Doctrine.