Abrogail put Detect Magic up for that but does not have nearly the Spellcraft required to interpret it. 

So it didn't detect her Evil alignment aura or the fact that her magic comes from the blood of Hell in her veins. What is it looking for, necromancy? Who the fuck does mind control with necromancy?

"Sorry," says Twilight to Abrogail with a slight nervous laugh. "Looks like they overreacted a bit."

"Hold it right there," says an orange earth pony with a pronounced country drawl. "I'm still not sure there ain't somethin' fishy about all this."

"I'll ask the Princess about her," she replies. "I mean, not that I wasn't going to anyway, but—in the meantime, I appreciate your concern, but I'm fine. Remember Zecora? We already learned this friendship lesson once. She's not going to hurt me or mind control me or anything."

(This is true. Abrogail kind of vaguely objects to it being true, but she isn't going to cause problems while the local god-queen is in town.)

"Alrighty then," says Applejack, and the five ponies file out of Twilight's bedroom.

A little while later trumpets herald the arrival of Princess Celestia, an enormous white winged unicorn twice as tall as an ordinary adult pony, riding in a flying carriage drawn by armored white pegasi. All the ponies gathered in the town square for her arrival bow as she steps out of her carriage, her ethereal iridescent mane fluttering in a nonexistent breeze.

—they all bow except Abrogail, who curtsies slightly in a manner appropriate for one monarch greeting another on the latter's territory. Also, this would be a great opportunity to look at a bunch of people with Aura Sight. (Disguise Self will hide the glowing eyes.)

None of the ponies have visible auras except for Twilight's presumed adventuring party, who all have faint auras in various flavors of Good. Celestia's aura is Neutral Good, with the quality of an outsider's rather than a mortal's, and unsurprisingly bright enough to blind her.

"Your Highness," says Twilight, trying to continue looking at the Princess and not at Abrogail conspicuously not bowing. "This is Abrogail, the Queen of Cheliax, which we think is in another plane—"

Twilight's voice suddenly seems to fade into the background.

She is not Intimidated but aaaaaahhh why is the god-empress looking at her.

"I know who you are," says Princess Celestia in Infernal. "I know what you've done. I do not believe that that is who you are, nor are you here to be punished. But if you try to hurt my little ponies, you will fail. Do you understand?"

okay now she's Intimidated

"I do. Why am I here?" she answers in the same language.

"This is an informally-reciprocated-consideration for a—" fuck this language. "A favor for a friend," she continues in Equestrian. (Infernal, of course, lacks the word 'friend'.) "She could not let you go free anywhere Asmodeus could reach you, but did not wish to imprison you forever. Here you are safe from Asmodeus, you cannot hurt anyone, and you might, perhaps, learn true friendship. At least, that is what we hope."

So Iomedae has dumped her in Nirvana, even if they're not calling it that and even if it isn't actually the same place Neutral Good petitioners go. She peers at the sun symbol on Celestia's flank. "You wouldn't happen to be related to the goddess of redemption and the Sun that I'm familiar with, would you?" she says.

"I think," says Celestia, appearing deep in thought for a moment, "that I was once a petitioner in Her afterlife, a little girl transformed in death into her favorite animal. In truth I cannot really remember. That was a very long time ago. I do remember my sister and I deciding to leave. We had—a number of disagreements with the powers there. So, no, I am not the Dawnflower, similarity in symbolism notwithstanding."

Abrogail is kind of curious about what differences of opinion She has with Sarenrae, but this conversation is probably on a time limit and she has more important things to say.

"Am I free to leave?"

"You may leave Equestria if you wish. You may not go back to Golarion, or to Hell."

"Which does remind me: where is Aspexia?"

"Turned to stone at the edge of the forest a few miles outside Ponyville."

"That rather violates the spirit in which you were both sent here, I think."

"She would honestly have preferred eternal petrification to what you have in mind for us, I'm quite sure. That isn't why I did it, but it's true."

The Princess sighs. "She is, from what I've heard, a very strange person. You may be right. I'll speak to her, and if she truly would prefer death to redemption, I will give it to her."

Would Sarenrae do that? Chelish theology textbooks explicitly say no but she has no idea of the actual answer. Celestia did say she had some differences of opinion with Her.