Darkheart

The Darkheart was a device constructed by Chronovores to heal their young and sick. The Darkheart is capable of altering timelines without causing paradox or attracting the attention of various "higher beings" (such as Time Lords or Chronovores) and as such could be used as a weapon. The Master schemed to use the device in this manner. As a demonstration of it's power, he changed the timelines of the crew of a Federation cruiser, making all non-humans into humans unless there were too radically non-humanoid (the Alpha Centauri and Xarax crew for example were simply erased from history). As far as the affected crew were concerned, they were always human (for example, the Draconian first officer believed himself to be a human lord from the planet Draconia). The Master later offered Terrel the destruction of Terileptus, using the device. In addition to the alternation of timelines, the device could be used to lock a person's timeline, making them effectively immortal. (MA: The Dark Path)