Tigus

Tigus was an uninhabited planet with high levels of volcanic activity due to it being quite a new planet. The Doctor referred to it as "a young planet, cooling down," which orbited a sun with "unusual powers" in "that particular galaxy."

The Monk attempted to strand the First Doctor and his companions there, but the Doctor figured out how to escape in a few minutes. (TV: The Daleks' Master Plan)

The planet was protected under the Galactic Heritage. (PROSE: The Tomorrow Windows)