The Tantalus field device
In the mirror universe, the Tantalus field is an alien device that vaporizes victims at the touch of a button. James T. Kirk used it to become captain of the ISS Enterprise. (TOS episode: "Mirror, Mirror")
History[]
It was one of the secrets that Tiberius was able to gain from the First Federation representative Balok before he was killed. (TOS novel: Dark Victory)
Spock took possession of the device upon his assassination of Kirk and used it to eliminate his political enemies, including a mutinous Uhura and Empress Hoshi Sato III. Spock was able to use it with more frightening efficiency, as he was able to wipe out the entire crew of a Klingon battlecruiser and a Romulan Bird-of-Prey within a year of taking control of it. These incidents - plus the "disappearance" of Uhura for plotting to mutiny against Spock lead to rumors that Spock is unleashing some previously unknown Vulcan psionic power. The Tantalus field's power fuels a rapid rise through the imperial ranks that, by 2277, culminates with his becoming Emperor of the Terran Empire. In 2293, after announcing the foundation of a Terran Republic, Spock knowing the Republic will be short lived destroys the device with a phaser to prevent another tyrant from taking possession of it. (TOS - Mirror Universe novel: The Sorrows of Empire)
In 2367 of an alternate mirror universe, Jean-Luc Picard looked up Spock's history, and finds that he managed, briefly, to become a very powerful and influential figure in the Empire, largely because his enemies had a way of "disappearing" when they became too threatening. (TNG novel: Dark Mirror)