- You may be looking for Battle TARDIS.
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 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)
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)