10 Deadliest Alien Prisons In Doctor Who

The Confession Dial was a Time Lord device designed to capture the Last Will and Testament of a dying Time Lord, but it could also be repurposed as a deadly torture chamber.

Appearing throughout series nine in the Twelfth Doctor's possession, it was finally utilised in 2015's Heaven Sent to trap him and demand he confess a dark secret. Teleported inside the device, which was bigger on the inside and resembled a clockwork castle, the Doctor was forced to live out his days on repeat until he decided to confess. Only when he revealed his knowledge of a dangerous 'Hybrid' would the Time Lords allow him to go free.

The Doctor was then tailed around the corridors and rooms of the constantly-shifting castle by a monster from his childhood nightmares known as the Veil. Lumbering after him and demanding confession, the Doctor decided to hold his tongue and escape from the Dial 'the long way round'.

For four and a half billion years, the Doctor repeated the same day over and over again - being killed and reborn, with his memories being wiped every time. Eventually finding the exit behind a wall of sheer diamond, the Doctor used his millions of years of imprisonment to slowly chip away at his escape route.

Finally breaking free by gradually punching a hole through the diamond, the Doctor escaped from the Confession Dial. Finding himself back on Gallifrey, he vowed to return to the Time Lord Citadel and find out who was responsible for his torture.

Intergalactic Travel Advice: Try not to run out of corridor.