Tantalus field

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. 

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 $𝜇$ and Empress $𝜇$. Spock was able to use it with more frightening efficiency, as he was able to wipe out the entire crew of a $𝜇$ 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, $𝜇$ looked up $𝜇$'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)