The Timonic Fusion Device was a temporal weapon often theorised about, but thought to be impossible to create. A component of its construction was Black light rods. A secret project on Gallifrey called Project: Alpha succeeded in building a prototype, but it was claimed that the device was unstable and dangerous and was thus dismantled. In reality, the device had been stolen right before the first detonation. Not wishing to be responsible for the loss of such a powerful weapon, the team told Irving Braxiatel that they had dismantled it. Very few Time Lords knew that the weapon had ever existed; even fewer knew that it was still operable. It was described as “napalm of the timeline” by Narvin and “a dirty, indiscriminate little weapon that should never have left the drawing board” by Braxiatel (AUDIO: Weapon of Choice).
A Timonic Fusion Device was used by the subversive organisation Free Time, although the weapon was never detonated due to Free Time being unwittingly used as a pawn in a greater scheme put in place to discredit President Romana. (AUDIO: Weapon of Choice, Square One)