b997eee8_CCG___What_s_That_Inside_Joke___In_joke
[Card] Flavia - Chancellor [Exp.] LoT [Type] Ref [In-joke] 
Her vortex uses the word "voice" because of New Who's contention that the "voice of Flavia" is heard singing on the show's soundtrack.
Unauthorized Dr. Who CCG - What's That Inside Joke?
In-joke