Tersurus

Tersurus was a planet with singing stones and clone banks. (PROSE: All-Consuming Fire) It was mentioned as being in the "Outer Planets" in the Matrix. (AUDIO: Neverland)

History
In the Old Time, the Other sent Susan Foreman to Tersurus during the Great Schism so that she would be safe from the civil war erupting on Gallifrey. (PROSE: Lungbarrow)

Following a ploy with the Daleks on 22nd century Earth, travelled with Susan Foreman in his his TARDIS to Tersurus, where she believed she killed him. However, the Master survived and attempted to attack a Time Lord outpost on the planet, only be confronted and left disfigured by, as part of his plan to join the Cult of the Heretic. Once the Cult's plans had been defeated and the crippled returned to this time period, a signal sent to Gallifrey by his TARDIS drew Chancellor Goth to Tersurus. (PROSE: Legacy of the Daleks, AUDIO: The Two Masters, TV: The Deadly Assassin)

The Time Lords had an outpost on Tersurus. The Master infiltrated this base on another occasion in order to gain forbidden knowledge on the Dimensioneers. (AUDIO: Dominion)

After his TARDIS was damaged by a vortex parasite, the Eighth Doctor patched it up on Tersurus. (COMIC: A Life of Matter and Death)

In 6211, a Sontaran stealth raid destroyed Tersurus with an earthshock bomb which they had obtained from the Cybermen. (PROSE: The Crystal Bucephalus)

The Curse of Fatal Death
Tersurus is a setting in the Comic Relief special mini The Curse of Fatal Death, which this wiki does not consider to be a valid source. In the special, a Time Lord known as the Ninth Doctor accompanied by his companion, Emma, meets with the Master on the planet to tell him the news that he has plans to marry her and retire.

The special also gives details on the natives of Tesurus, the Tersurons. The Doctor explains to Emma that the Tersurons were a kindly, peace-loving race, but shunned and abhorred due to their communicating solely through precisely modulated farting. They destroyed themselves after discovering fire.

The Master makes one final attempt to destroy The Doctor and his Companion, Emma by plunging them into the vast, labryrinthian Sewers of Terserus. The Sewers being so vast and complex, as well as disgusting and treacherous, that it takes The Master 300 years to escape from them.