Profane Virus of Rassilon

The Profane Virus of Rassilon was a creation of the Time Lords.

It was a nanovirus created by Gallifrey's greatest nano-engineer Erkulon who made it as a last resort to prevent aliens from obtaining his people's technology by destroying all of it. The virus was capable of overriding and reprogramming any exitonic circuitry.

A sample of the virus was stored in the Slaughterhouse on Gallifrey where a portion of it was stolen by the Master. (PDA: The Quantum Archangel) He infected TOMTIT with it, presumably during the events of DW: The Time Monster, in the hope that the Third Doctor would attempt to use it to follow him to Atlantis. However, the Doctor did not trigger the Virus until the events of The Quantum Archangel. It caused the Doctor's TARDIS to Time Ram itself nanoseconds in its own past. However, The Doctor was saved by Kronos, in the guise of Paul Kairos.