Phila was a brief companion of the Master.
When the Master asked for a pilot so he could use a landship to search for an energy source, which was rumoured to be why Arcking had such mysterious properties, he requested Cole Jarnish as a pilot, alongside Phila as a companion, albeit briefly. Upon finding the source, they found that it was sentient. After leaving it, due to it talking to them and refusing to go, their landship was attacked by Daleks, and they were forced to leave it. Phila was killed, and Cole left Arcking with the Master in his TARDIS. (AUDIO: The Good Master)