Tersurus

Tersurus was a planet that had singing stones and clone banks. (PROSE: All-Consuming Fire)

In the Old Time, the Other sent Susan Foreman to Tersurus during the Great Schism so that she would be safe. (PROSE: Lungbarrow)

Following a ploy with the Daleks on 22nd century Earth, travelled with Susan Foreman in his TARDIS to Tersurus, where she believed she killed him. During the encounter, his TARDIS sent a signal to Gallifrey that brought Chancellor Goth to Tersurus, where he found. (PROSE: Legacy of the Daleks, TV: The Deadly Assassin)

The Time Lords had an outpost on Tersurus. The Master infiltrated their base in order to gain forbidden knowledge on the Dimensioneers. (AUDIO: UNIT: Dominion) It was mentioned as being in the "Outer Planets" in the Matrix, possibly meaning it was in Kasterborous or even Gallifrey's system. (AUDIO: Neverland)

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

The Curse of Fatal Death
Tersurus is a setting in the Comic Relief special, The Curse of Fatal Death, which this wiki does not consider to be a valid source. In the special, a being 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 Emma 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.