Ercos

Ercos was a planet in the Relram system, inhabited by the Klims, which the Fourth Doctor claimed was his favourite planet.

History
The Daleks invaded Ercos and a Dalek camp was set up, in which the Klims were enslaved and put to work. At the will of the Time Lords, the Fourth Doctor and Sarah Jane Smith arrived on the planet and stopped the Daleks from using the Dalek driller the enslaved Klims had helped them build, which they intended to use to destroy Ercos and Earth. (COMIC: The Dalek Revenge)