War TARDIS

War TARDISes were created by the Time Lords to fight during the Vampire Wars (PROSE: So Vile a Sin, Doctor Who and the Krikkitmen, et al.) and the War in Heaven. (PROSE: The Taking of Planet 5, et al.) These included Type 91s (PROSE: The Book of the War, The Brakespeare Voyage) and Type 94s. (PROSE: The Quantum Archangel)

Characteristics
War TARDISes were reared/born/controlled via a Bull-TARDIS in the time vortex. (PROSE: The Taking of Planet 5) Though not recognisably intelligent, the minimum-intensity biodata in their structures gave them a biological edge, suggesting they were aware of life on their pilots' level. (PROSE: The Book of the War)

They were programmed with self-preservation, so rather than changing to match the personality of their owners like many other TARDIS models, they worked to change the personality of their owners. (PROSE: Doctor Who and the Krikkitmen)

They could map their interior dimensions onto the outer dimensions, making for an imposing sight. (PROSE: The Ancestor Cell) In fact, 91-forms were the first timeships intentionally designed to be indiscreet, appearing as consistently big, bulky, and unapologetic. In orbit, they were often mistaken for arks or flagships of lesser species; however, they more often rooted themselves on planets at ground level, pushing aside buildings and taking the forms of giant cathedral-like embassies for the Great Houses. Some such grounded 91-forms were incapacitated or abandoned and dug out of the group millions of years in the localised future, misidentified by the natives as relics of a lost civilisation or the bones of huge, semi-mechanical monsters. (PROSE: The Book of the War)

They could not withstand many shots of weapons fire from the first Type-102 TARDIS known as Compassion. (PROSE: The Ancestor Cell)

Older versions, built during the Dark Times when the Time Lords fought the Great Vampires, were the size of comets and had unstable real world interfaces. One was damaged in the War and became known as the astronomical body Cassandra. (PROSE: So Vile a Sin)

Uses
Twelve original War TARDISes were created for the Great and Terrible Wars against the Vampire Mutations early in Gallifreyan history. They were intended as an expensive, short-term measure, but with their self-preservation instinct, they influenced their handlers to maintain the fleet in case of future conflict. After a millennium, the TARDISes were finally used again in the Krikkit War, during which one was lost and the other eleven were put back into storage. Foreseeing the possibility of its kind being decommissioned, this lost War TARDIS influenced its owner during the peace talks after the Krikkit War to set in motion a series of event that would lead to a second Krikkit War and the revival of its kin. (PROSE: Doctor Who and the Krikkitmen)

"Military TARDISes" were sent to collect the Sixth Doctor from Etarho in a displaced timeline. (AUDIO: Trial of the Valeyard)

House Mirraflex used 91-form variations in their assault on the City of the Saved. (PROSE: The Book of the War)

When the Master came under attack by the Divine Host of the Chronovores, the Quantum Archangel altered reality and changed his TARDIS into a "Type 94" War TARDIS, armed with Klypstrømic warheads, an artron cannon, a vortex lance, and Earthshock bombs. (PROSE: The Quantum Archangel)

Kenossium flew a Type 94 to the Gates of Elysium during the Last Great Time War. Type 91s were part of his strike force. He used the TARDIS to place a tractor beam over the Doctor's TARDIS and save him from the Nightmare Child. (PROSE: The Third Wise Man)