Straxus' TARDIS

Straxus owned his own TARDIS. Sandun was a technician that helped him pilot it.

He used it to save the Eighth Doctor and Molly O'Sullivan from a group of Daleks. It was attacked by the Daleks and he escaped back to Gallifrey. Straxus later travelled to Srangor to kill himself and prevent his future incarnation; Kotris, from ever being created, as regeneration was impossible there. (AUDIO: Fugitives)

After many attempts to find the Doctor, there was a power failure within the TARDIS. After this failure was corrected, they managed to find the Doctor. (AUDIO: Tangled Web)

Sandun sacrificed himself to make sure that the Doctor did Straxus' bidding, and show him that the TARDIS was time rammed with the Doctor's TARDIS. (AUDIO: X and the Daleks)