Is this an article about the planet, or the superweapon? Or are they one and the same? If not, then there may need to be separate Darkheart (weapon) and Darkheart (planet) pages.
Darkheart was a planet located in the gap between the Galaxy's spiral arms, connected to its star's mass via a dimensional bridge and it was the location of a device constructed by Chronovores to heal their young and sick. The Darkheart is capable of altering timelines without causing paradoxes or attracting the attention of various "higher beings" (such as Time Lords or other Chronovores) and as such could be used as a weapon. The Master schemed to use the device in this manner. As a demonstration of its power, he changed the timelines of the crew of a Federation cruiser, making all non-humans into humans unless they were too radically non-humanoid (the Alpha Centauran 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 Terrell 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. (PROSE: The Dark Path)