Ah, so that's where Clara is. I'm wondering if they're testing out Ashildr as the new companion.
Well, duh, of course it's Ashildr. Even if I hadn't recognized her under the mask - the DW Twitter couldn't help itself and spoiled it. Good thing I've unfollowed it now.

Really, she does that voice without technological help or anything? ô_o

The Doctor seems to forget that he's a time traveller and that Ashildr might just know those things about him from another encounter she's already had with him, but hasn't yet happened in his timeline.

No one was good enough for the 2nd immortality charge? Not even one of her parents?

Good thing that although the portal is fed by Sam's life force, his infinite life force doesn't feed the portal.

I'm glad that Jack is mentioned. And I'm happy that it sounds like we'll see Ashildr again.