DM: After a few minutes of, uh, I guess fake sobbing... you sense that–
Twilight Sparkle: "I know you're there."
Princess Cadance: Haha! Saw that one coming, did you?
Twilight Sparkle: I was kind of counting on it, in fact. You were being sneaky all day; I have no trouble believing you could double back without anypony else noticing.
Princess Cadance: Well done.
DM: Yeah, some of her soul-reads have been absolutely ridiculous.
Twilight Sparkle: Anyway, I say: "Take me to her."
DM: Uh... you're going to say that straight out of the blue?
Princess Cadance: Cadance just smiles.
It's a good thing we already know what happens in canon, otherwise this tactic would seem stupidly suicidal. For all Twilight knows, Cadence could just kill her here and now.
To be fair canon doesn't have to mean anything in this comic. The Elusive arc went totally off the rails in an awesome subversion of canon expectations! Do I think that will happen again this time? Probably not, but as long as the possibility exists Newbiespud is free to put on his best "smiling DM" face and watch us scurry in the comments.
Well, she probably didn't have to worry about Cadence murdering her right in the throne room. Cleaning up the body from there would've been too much of a risk.
I'm actually very curious what the twist is going to be.
Trapped Cadence is real Cadence but the twin is a deliberate summons and psychic vampire channeling power back to the original?
Trapped Cadence is fake Cadence but the pressure of keeping her in there is affecting the original with fake Cadence's personality?
Trapped Cadence and Cadenza are the same pony split into good and evil versions by Shining as some kind of perfection spell gone wrong?
Twilight is an epic level wizard with a relatively loyal party, two of which are loaded (though their assets might literally be frozen in Ponyville right now). If she dies she'll be fine.
Oh, I know, I'm just poking at Twilight's assumption that the real Cadance is still alive. Considering that Cadance was invented as part of the hook to get the brother and his fiance into the game as guests, she could easily have been already dead in the backstory as far as Twilight knows.
Cadence looks very strange in the last panel - part her large alicorn eyes and part Uncanny Valley (for ponies). A deliberate choice by the animators, I expect.