As well as bringing together multiple incarnations of the Master, this story both explained and depicted the genesis of the Ravenous, inadvertently caused by the ancient Time Lord engineer Artron, as well as their end, by Artron's own command, as he returns them to their Kolstani forms.
By visiting Artron around the time of his discovery of artron energy, and before the start of the Rassilon Era, this story depicts Time Lord history at an early point in their history along with Collision Course, which featured the first prototype TARDIS while this one features a fleet of battle TARDISes placing it afterwards.
Liv Chenka and all others within the same time zone temporarily gain the ability to regenerate, like Time Lords, but indefinitely, and without changing form. The man who granted Helen's wish in Fairytale of Salzburg is also revealed to have been Artron.
With regards to the Master's timeline, Day of the Master finally explains how the maniacal Time Lord's twelfth and final regeneration, once more in decay, managed to acquire a new regeneration cycle. Three incarnations of the Master watch as he regenerates into a familiar body.
The Doctor investigates a mystery in the vortex, Liv follows the trail of their enemy, and Helen searches for a god. Everywhere they go there is a Master or Mistress, but is the Doctor's oldest enemy there to hinder them, or to help? With the TARDIS crew scattered and lost, only a miracle can save the universe. And for that to happen someone is going to have to die.
to be added
- The Doctor - Paul McGann
- Liv - Nicola Walker
- Helen - Hattie Morahan
- The Eleven/The Eleven - Mark Bonnar
- The Master - Eric Roberts, Derek Jacobi and Geoffrey Beevers
- Missy - Michelle Gomez
- Ravenous 1 / Kolstani 1 - George Asprey
- Ravenous 2 / Kolstani 2 / Valcon - Susie Emmett
- Artron / Cadrin - Robert Whitelock
- In Artron's time, Rassilon is still experimenting with regeneration.
- When working out his identity, Liv believes the War Master to be an incarnation of the Eleven, guessing he is the Twelve, the Thirteen, the Four, or the Six, in that order.
- The Doctor thinks Missy could be an incarnation of the Rani, saying that the Master and the Rani have worked together in the past.
- When the War Master suggests wiping the "Bruce" Master's mind and throwing him into the vortex, Missy mentions River Song, and states that she wouldn't object to trying her methods of mind wiping on the "Bruce" Master.
- The Doctor briefly assures himself he has no need to regenerate, and then wonders if he is still fit to do so after his attack from the Ravenous.
- Regarding the War Master and Missy being in Ravenous 4, Dorney said there would be no amnesia involved. Indeed, the Doctor never meets them in person, nor does he learn they are future incarnations of the Master. Although Liv describes the War Master, and identifies him by name, the description is sufficiently vague for the Doctor to muse that it could be any Master, while Helen only ever discovers Missy is a Time Lady who knew the Doctor, leaving the Doctor to theorise that she may be the Rani.
- The Doctor notes that the Master and the Rani have worked together in the past. (TV: The Mark of the Rani)
- River Song once teasingly mistook Missy for the Rani. (AUDIO: The Bekdel Test)
- The Crucible of Souls is used by the Ravenous and the Eleven in their grand plan. The Crucible was previously a part of a plan by the Nine and the Doom Coalition. (AUDIO: The Crucible of Souls)
- The War Master is granting his past self a new regeneration cycle as part of a deal with the CIA. (AUDIO: The Devil You Know)
- The War Master declares that his past self would have "a new body, at last". (TV: The Keeper of Traken)
- Missy says "Hello you" to the "Bald" Master. (AUDIO: Dominion)