Rassilon (The End of Time)

Late into the Time War, a new incarnation of Rassilon led the Time Lords against the Daleks. One of his proposed last resorts to win the War was the implementation of the Ultimate Sanction.

Wartime
During the Time War, Rassilon was taken to the Death Zone by Pandoric to offer advice to his former self in whether to use the Galaxy Eater to destroy the Nestenes. He warned his former self that he would live past his death and that there would be even greater conflicts in his future. (PROSE: Pandoric's Box)

When the Time Lords feared that the Compassionate would side with the Daleks in the Time War, Rassilon sealed them in a rift at the heart of the planet Galen and told the War Doctor that the Daleks had done this. (AUDIO: The Bleeding Heart)

Rassilon retro-evolved dozens of Time Lords to become a possibility engine to aid him in victories throughout the Time War, creating the discarded race of the Interstitials and succeeding with Borusa.

Late into the Time War, Rassilon sent the War Doctor on a mission to find the War Master after he had fled the War. (PROSE: Engines of War)

Last days of the Time War
Four-hundred years into the War, Rassilon planned to detonate the Tear of Isha in the Tantalus Eye to stop a Dalek plan to wipe Gallifrey and the Time Lords from history. He consulted Borusa on his plan, who told him it would succeed. Rassilon's plan was foiled by the Doctor, who stole Borusa and the Tear of Isha, using Borusa to wipe the Daleks from the Tantalus Eye without killing all life around it. Rassilon condemned the Doctor's actions and made him an enemy of the Time Lords because of it, (PROSE: Engines of War) exiling him from Gallifrey. (PROSE: The Whoniverse)

On the last day of the Time War, Rassilon intended to spare Gallifrey from destruction by using the Ultimate Sanction to turn the Time Lords into beings of pure consciousness to escape the end of creation. The Woman opposed Rassilon's plan to destroy time itself, (TV: The End of Time) along with the Patriarch of the House of Stillhaven. (PROSE: Lords and Masters) Rassilon condemned them to stand behind him in the Panopticon and cover their faces "as monuments of their shame, like the Weeping Angels of old", (TV: The End of Time) and had their names erased from time as further punishment. (PROSE: A Brief History of Time Lords)

Knowing that the Doctor intended to destroy both Time Lords and Daleks by using the Moment, Rassilon contrived to break Gallifrey out of the time-lock that blocked the Last Great Time War from temporal manipulation, and then follow through on his plan. He succeeded. For a brief time, Gallifrey broke free of the time lock and appeared in the skies above Earth. However, Rassilon was opposed by the Tenth Doctor, one of only two Time Lord survivors of the war. Rassilon was badly hurt by one last attack by, the other survivor, out of vengeance once he realised that Rassilon had deliberately driven him mad and destroyed his life. The time-lock resumed and Rassilon, the Time Lords, and Gallifrey itself were all flung back to the Time War. (TV: The End of Time)