A Time Manipulator was an immense conjugation of time particles and brain cells, described by the First Rani as "a cerebral mass (the size of a planet) capable of dominating and controlling time anywhere in the cosmos." (PROSE: Time and the Rani) Operating on a grand scale, it was able to change the order of creation.
The Rani planned to use the Time Manipulator to change the history of any planet in the belief she should intervene in the evolution of various species.
History[]
The Rani attempted to transform Lakertya into a Time Manipulator, feeling it wouldn't be necessary if the Time Lords hadn't refused the intervene in the evolution of other species. With this "monstrosity," as the Doctor called it, the Rani would be able to redirect evolution wherever she felt it had taken the wrong route. She planned to return to Earth in the Cretaceous Age, feeling the potential of the dinosaurs was never fully exploited.
The Doctor was able to delay the countdown of the launch, causing the missile to miss the asteroid. In the process, the Brain was destroyed, preventing the Time Manipulator from existing. (TV: Time and the Rani/PROSE: Time and the Rani)
Similar technology[]
Jodafra called the Windigo a "Time Manipulator" as it's screams could paralyse time-fields, essentially freezing individuals between seconds. (COMIC: Bad Blood)
Before evolving into their current plane, the Chronovores' ancestors built the Darkheart, a space/time conduit that could transmit energy to any point in time and space. Unlike a TARDIS, the Darkheart had direct access to time. Whereas history could not be changed without creating an alternate timeline, this was only true when travelling in a TARDIS as the Darkheart actually reshaped the universal matrix to account for changes that were made. (PROSE: The Dark Path)