Battle TARDIS

Battle TARDISes were the usual type of TARDIS used in battle.

Characteristics
Contrary to the Doctor's Type 40 and other conventional TARDISes designed for time travel without the threat of attack and for scientific research and exploration missions, these TARDISes were equipped with heavy armaments to engage in battle at a second's notice while being flown into hostile locations. The Celestial Intervention Agency made significant use of them.

Their outer plasmic shells were composed of living metal, able to morph into shields and any number of predetermined gun emplacements. (PROSE: Engines of War) Their main weaponry were time torpedoes, (COMIC: The Stockbridge Horror) which could be used to freeze time and thus suspend other vessels in the time vortex. (AUDIO: Neverland)

Battle TARDISes were as sentient as other TARDISes, to the point that their experiences were recorded by the Matrix upon their destruction, much like their Time Lord pilots'. (COMIC: Sky Jacks)

History
The CIA used at least one Battle TARDIS, commanded by Tubal Cain, to capture the Fifth Doctor after he had brought an elemental being to Stockbridge. (COMIC: The Stockbridge Horror)

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

A flotilla of Battle TARDISes were sent to gather the Eighth Doctor and Charlotte Pollard for the fight against anti-time. The Doctor initially avoided them (AUDIO: Embrace the Darkness), but they eventually caught up to his TARDIS and snared it with time torpedoes. (AUDIO: Neverland)

The Battle TARDIS Program was restarted by the Doom Coalition, with Battle TARDIS Δ being used by Captain Veklin. (AUDIO: The Crucible of Souls)

Romana III cleared out large sections of Gallifrey in order to make room for more Battle TARDISes. These Battle TARDISes would then join the fight in Gallifrey's "darkest hour". (AUDIO: Luna Romana)

Over a million Battle TARDISes were used by the Time Lords in the Last Great Time War. (PROSE: Peacemaker) Cardinal Ollistra travelled to Synthesis Station in a battle TARDIS. (AUDIO: Day of the Vashta Nerada) The General led a strike force of Battle TARDISes to the Gates of Elysium. (PROSE: The Third Wise Man) A flotilla of Battle TARDISes were destroyed by Dalek stealth ships near the Tantalus Eye. Rassilon later sent another flotilla to the Eye to deploy the Tear of Isha. (PROSE: Engines of War) On the final day of the war, Priyan stated that every Battle TARDIS had been destroyed. (COMIC: Sky Jacks)

The Battle TARDISes had been rebuilt by the time of the Coup against Rassilon. When the corrupt founder returned, backed by the full might of the Cybermen, he manipulated the Eye of Harmony to depower every TARDIS, preventing the Time Lords from sending the Battle TARDISes back to undo the invasion. (COMIC: Supremacy of the Cybermen)

Alternate timelines
In an alternate universe where the Time Lords sold their technologies to other races, they gave Battle TARDISes to the Killorans. (AUDIO: Reborn)

In an aborted timeline, a version of the Master from a parallel universe seized control of Gallifrey and ordered all 2,000 Battle TARDISes to be deployed against an entropy wave that was consuming the universe, armed with dimension inverters. Once they were in position over Gallifrey as the wave approached, the Master activated the inverters whilst they were still onboard the Battle TARDISes, destroying all of them, Gallifrey and the Eye of Harmony. This failed to stop the entropy wave. (AUDIO: Masterful)