Eternity Cage

An Eternity Cage was a Time Lord stasis environment used to hold prisoners in suspended time.

During the Last Great Time War, Eternity Cages were a feature of Battle TARDISes. After Vassarian's Battle TARDIS had been damaged to the point of a crash landing, the Time Lord ejected his ship's Eternity Cage, intending to wait out his TARDIS' repairing itself. As the Cage sealed around him, Vassarian began to regenerate, the Cage preventing the process from completing. In this state, Vassarian began leaking artron energy, a signature that was detected by the Sontaran Empire.

Brought to Rovidia, the Eternity Cage was used by the Sontarans to fuel their time technology. Seeking revenge against the Sontarans, Vassarian manipulated them into abducting the War Ollistra so the Sontarans would reach out to the Dalek Empire whereupon Vassarian would dissipate the artron energy and leave his captors defenceless. Finding he was too weak to do so however, Vassarian only managed to dissipate the energy with the aid of the War Doctor, the Eternity Cage shutting down. As the War Doctor and his companions escaped in Vassarian's TARDIS, the Eternity Cage was destroyed in the Dalek Fleet's orbital bombardment. (AUDIO: The Eternity Cage)