Fenris' time-jumper. (COMIC: Star Death)
The time-jumper was a time travel device used by the Order of the Black Sun, 30000 years after the disappearance of the Time Lord Omega.
It was a portable device, worn with a belt. It let its bearer to "time jump".
Fenris the Hellbringer employed one to travel back to the early days of Gallifreyan history, charged with averting the dawn of the Time Lord civilisation. His attempt was foiled by Rassilon, who eventually took from the time-jumper the directional control device, a piece of technology still missing from the Gallifreyan time travel technology. (COMIC: Star Death)