32. The Stolen Earth/Journey's End 4.12-4.13
There are many reasons to love this companion showcase, where everyone important to the Tenth Doctor comes together to help him save the world from one of the most sophisticated alien plots yet. It is a true chance for all of their own abilities to shine, driving home the point all of the first four series has tried to drive the important of the humans in the Doctor's life. It is also a heartbreaking companion departure, as this story leaves the Doctor alone again by the time it concludes. It is a rare occasion where the Doctor displays some Time Lord powers, something we have not really seen since the era of the Fourth Doctor's hypnotism. It is also the only time where the TARDIS is properly piloted, in truly adorable and dorky TARDIS family fashion. But it is most important for being an aborted regeneration, whose after effects result in an apparently first-ever in the universe metacrisis.
31. Attack Of The Cyberman 22.1-22.2
Worthy of being remembered for that one time that the Doctor got the chameleon circuit working...er well almost. The TARDIS, of course excited, changes even though she lands in junkyards, places where the standard police box was perfectly suitable. The serial sees yet another model of Cybermen and this Doctor's reign of violence continues as he casually jabs a sonic lance into one. But perhaps most surprising is the conversation which closes the serial. DOCTOR: It didn't go very well, did it? PERI: Earth's safe. So is history and the web of time. DOCTOR: I meant on a personal level. I don't think I've ever misjudged anybody quite as badly as I did Lytton. It is noteworthy one because it demonstrates how far the Doctor has come as a meddler that the safety of time is clearly no longer his primary concern. But secondarily it is the Doctor admitting unequivocally he is wrong. In his many centuries roaming about through space and time he has trouble admitting he is wrong about anything. At best he begrudingly admits to accidents or miscalculations, now and then. A surprising declaration for one of the most arrogant versions of the Doctor to date.