The War King

The War King was an incarnation of the Master that became the leader of the Time Lords during the Second War in Heaven.

Rise to power
During the events of the Second War in Heaven, the War King was captured and interrogated about his world by the agents of the Enemy. The War King managed to escape, but the torture deeply affected the War King, it made him realise how he cared for his people. The War King concluded that he would help the Time Lords in any way he could. Common rumours said that he just took advantage of this opportunity to gain the immunity for his past crimes and the power over Gallifrey.

The War King arrived on Gallifrey and told the Time Lords of what he had witnessed and vowed to help the Time Lords in any way they wished. President Romana refused to accept the Enemy's existence and their threat to Gallifrey and she warned the War King that if he ever returned to Gallifrey to unsettle Time Lord society with speak of a War; he would be arrested for his previous crimes against the Time Lords.

The War King's actions on Gallifrey had caused some Time Lords to investigate the existence of the Enemy and their threat to Gallifrey, to which the Time Lords discovered that the Enemy was a credible threat and had the power to destroy the Time Lords. Some Time Lords took this further and suggested that the War King be pardoned of his crimes so he could become part of a future war effort.

The War King saw this banishment as a mere setback and began to devise ways for the Time Lords to combat the Enemy, the War King then spent over 40 years creating plans for new weapons and devices. With the plans he had created, the War King travelled back to Gallifrey in his TARDIS and was captured by the Chancellery Guard, where he denied none of his offences. He then asked for an emergency meeting of the High Council to propose his plans. During the emergency session the Time Lords accpeted that the War King had told the truth and concluded that Gallifrey would need a new leader with military experience. The War King was the obvious candidate and the Time Lords wiped all records of the War King's past and made him War King of the Nine Gallifreys. (FP: The Book of the War)

As War King
The War King was cloned during the War, this clone was killed by Father Kreiner who kept his head as a trophy. (EDA: Interference - Book One)

2 years after coming to power, the War King initiated a pact with Compassion; creating a "second front" for the War. (FP: The Book of the War)

The War King sent Homunculette to investigate the Elder Things. (EDA: The Taking of Planet 5)

50 years after the battle on Dronid, the War King hired House Lolita to destroy the Faction Paradox powerbase of the Eleven-Day Empire to stop the Faction from supplying weapons to the Enemy or sign a treaty of reconciliation with House Tracolix. (BBV: The Eleven Day Empire)

The War King later understood the true motive of Lolita, a sentient TARDIS, who had evolved from one of the Master's previous TARDISes. (CP: Toy Story) Lolita planned to reach the Eye of Harmony on Gallifrey that would enable her to contaminate the entire universe with her own biodata, so that she could rewrite the Spiral Politic to suit her own ends. The War King as a last resort, allied himself with the last members of Faction Paradox against Lolita. The War King's alliances failed and the War King was eaten by Lolita, who claimed for herself the title of War Queen. (FP: Words from Nine Divinities)

Fate
The Doctor, in a desperate attempt to avert the future chaos he had learned of; managed to erase the Second War in Heaven's timeline by destroying Gallifrey and restored the normal timeline to the universe. Therefore the events that enabled the War King to become War King of Gallifrey never occured. (EDA: The Ancestor Cell)

Behind the scenes
Due to copyright restrictions surrounding "the Master", stories in the Faction Paradox series refer to the character as the War King and play heavily on the fact that the character is the Master. However the Faction Paradox related short story: Toy Story written by creator Lawrence Miles confirms that the War King is the Master.