Arkheon

Arkheon, also known as the Planet of Ghosts, was a planet located near the Crab Nebula, just past the Pleiades, left at the Blue Star Worlds. Temporal echoes resembling ghosts roamed the surface due to a temporal fissures in the planet's core. The world was virtually destroyed by the Daleks.

History
During the First Dalek Incursion, Arkheon was hit by a "Planet-splitter" missile. The missile strike destroyed half of the planet, exposing the core. The fallout killed most of the inhabitants. The survivors eventually mutated into mindless, savage beasts.

Forty years later, the Doctor and the crew of the Wayfarer discovered that the Daleks had turned the area around the core into a slave labour mine in an attempt to locate the Threshold and use it to become masters of time. The Doctor defeated the Daleks, and Earth Command sent in forces that destroyed the remaining Daleks and freed the prisoners, and the Doctor sealed the Threshold,so the Daleks could not exploit it. (NSA: Prisoner of the Daleks)