Going by the theory that she is the one who got Clara involved with The Doctor to set all of this up she must have already known that he would get a new regeneration cycle.

She may not have realised he was running out on his previous cycle; would she have knowledge of 10.5? Either way, if she knew what the future events would be and went back to involve Clara then it's not really important because whether or not she knew about the new cycle she did know that Twelve would exist.

As with the War Council on Gallifrey when they counted Capaldi as the 13th Doctor of his first regeneration cycle Missy may not have known that Tennants Doctor had two goes on the roundabout.

So she may well have thought there would be one more Doctor after Smith.



It probably depends on where the Master has been recently.


If he was on Gallifrey and only escaped (somehow) though the Crack on Trenzalore then he probably does know Capaldi is the first of a new cycle.



If he never got stuck on Gallifrey but hid himself elsewhere then he may still think Capaldi is Doc 13 (Cycle 1).

This.

Does he/she really keep count?

The Master has a habit of blagging new lives whenever he needs them - stealing the potion from Karn, inhabiting 'temporary' bodies, etc etc so is probably not surprised that the Doctor hasn't apparently run out.

Also, if extra sets of regenerations are awarded, he might have assumed that the Doctor would be granted them, as he is generally a 'good man' - despite the grumblings of the High Council.

Moffat said the Doctor does not see himself as the 11th 12th or 13th Doctor. He's just the Doctor.

How would the Master then know how many regenerations the Doctor has had if the Doctor doesn't talk about which number he is?

The Master never encountered the War Doctor or Eccelestone, nor would he know Tennant regenerated twice. Come to think of it did he ever encounter the 6th Doctor?

He didn't meet 11 either.

It was once said (in classic Who, I think) that Time Lords recognise each other, even through regenerations. This being said, the Doctor has failed miserably to recognise the majority of Time Lords he's re-encountered. (He's actually a bit naff as a Time Lord - couldn't steer the Tardis at first, no control over his regenerations unlike some others, goes bonkers for a while after a regeneration.)

The Mistress is fully aware of the concept of extra regeneration cycles - she was offered one once by the Gallifrey High Council, along with a pardon, for assisting the Doctor during the Five Doctors. So she might not discount the possibility, even though Gallifrey is 'unavailable for use'.

Yes he did see the 6th Doctor in Time and the Rani he teamed up with the Rani

And in Trial of a Timelord.

Not just offered one she was given one YANA was the 1st regeneration of a new cycle.

Well as far as we know he was the first anyway.