Time Lord knowledge and their personality prints, captured at death in the Amplified Panatropic Computer (A.P.C net) that is a subsidiary part of the Matrix itself. The Key of Rassilon allows physical access to the Matrix, for maintenance of this 'micro-universe' repository of Time Lord knowledge. Confusingly, this is a separate artifact from the so-called Great Key of Rassilon, that provides direct tapping of the near limitless energies of the Eye of Harmony, and is cited as a vital component part of the demat gun (a weapon of mass destruction); it is also hinted that this 'key' is essential to accessing the other relative dimensions in time, in The Invasion of Time. The Rod of Rassilon (referred to as "the Great Key" in the Book of the Old Time in The Deadly Assassin) allows the user to physically access the containment/control apparatus of the Eye of Harmony itself, that was historically hidden beneath the Panopticon central dais. The Coronet of Rassilon gives the user the ability to amplify and to project their own will to dominate others, but its effects can be defeated, if recognised, by a co-ordinated resistance of many minds. The Harp of Rassilon is a musical key that unlocks a secret room within the High Council chambers. This hidden compartment held the controls for the Time Scoop—a rudimentary "time corridor" technology, used presumably before time travel was perfected by Rassilon after the installation of the Eye of Harmony on Gallifrey. The Ring of Rassilon ostensibly grants the wearer immortality, but seemingly is keyed to Rassilon's DNA only, so that any other seizing the artifact is locked in perpetual imprisonment as a stone carving relief on Rassilon's bier. The Black Scrolls of Rassilon are parchment documents containing forbidden knowledge from the Dark Time, not recorded in the Matrix. Rassilon is also given credit, variously, for TARDIS technology; the living metal and super-weapon validium; and the defensive Quantum Force Field and Transduction Barriers that protected Gallifrey. How much of this is true and how much of it is propaganda is not certain. However, it is established that a TARDIS derives its power primarily from the Eye of Harmony. The Tomb or Tower of Rassilon, also known as the Dark Tower, stands in the middle of the Death Zone—a blasted, barren plain—on Gallifrey. The Death Zone was used, in a period of Gallifrey's history known as the Dark Time, as