The Glory

The Glory was the focal point of reality.

History
At an unknown point in time, Esterath became controller of the Glory and kept it safe from all who would use it for evil.

Esterath became weary and sought a successor, he found the Master floating in the Time Vortex and saved him. Esterath gave the Master a new body and told him that there would be a fight over the Glory and the victor would be able to control the Glory itself.

The Master assumed that the battle would be between him and the Doctor. However, the Master was mistaken: the true battle was between his companion, Sato, and the Doctor's, the Cyberman Kroton. Kroton was the ultimate winner of this contest, and amongst his first acts as controller of the Glory was to banish the Master away from the Doctor's TARDIS into an apparently inescapable prison. (DWM: The Glorious Dead)