Curse of Fatal Death was really something. Shades of Missy, River Song, Eleven's aging in Day of the Doctor and maybe even Heaven Sent. The bit with the sofa reminded me of Deep Breath.
A couple of years ago, in the 50th anniversary special "The Day of The Doctor" we learned that The Doctor chose his name "Doctor" because of a promise:
Clara: You told me the name you chose was a promise. What was that Promise?
Tenth Doctor: Never cruel or cowardly.
War Doctor: Neve...
Another thing I noticed in Curse of Fatal Death was "never cruel and never cowardly". Is that another foreshadowing of modern Moffat, or was it always established as the definition of Doctoriness even in classic Who? @BESW