Maybe polymorph spells? Polymorph spells can do so many things...

Her blob whistles and buzzes, pointing towards the extradimensional spaces entry on the schedule. Alright then, extradimensional spaces it is!

The room labeled "extradimensional spaces" has three large mirrors inside it. A wizard stands to the side.

For a brief moment, a human face appears next to Tencednil in one of the mirrors. They wink and disappear.

"Are all the mirrors their own pockets?"

The shadow blob zooms straight towards one of the mirrors and pokes at it.

"They are. Each one fits eight people. There's room in all of them, currently. You can walk through the mirror's surface."

The shadow passes through the mirror's surface! It's now in an extradimensional space. There are some humans in here, who are confused at its appearance. If the shadow wants, it can make itself visible on the other side for six seconds at a time.

It bounces at them! Then it zooms back out and grabs at Tencednil's hood, tugging her towards one of the other mirrors.

What an opinionated blob. That was the plan anyway, no need to rush her. Over she goes. She reaches out her hand to touch its own reflection, and feels for the surface...

Her hand passes through the mirror's surface. It doesn't feel like anything.

Magic is so incredibly neat sometimes. Now confident she's not about to bash her head into anything, she walks confidently into the mirror.

The other side is a small room. The floors, walls, and ceiling are all made of a translucent, silvery material. It glows very slightly and is soft to the touch.

Five people are sitting around the room. One of them is an Acadamae student, reading a book. Another is running his hand across the wall.

Does the room seem cramped, like an eight-person room with six people in it would be? (Or with seven, if the shadow counts. It probably would for spell targeting, but maybe not if this is just a space with a size?)

The room is perhaps a little cramped. It is an eight-person room with seven creatures inside. (The shadow counts.)

What does the mirror look like from this side?

It looks like an open doorway into the room she just came from. The mirror's frame is the same, but there's no visible surface of any kind.

She can make herself visible as a reflection in the mirror on the other side for six seconds at a time, if she wants to.

Sure, she'll do that. She also nudges the shadow to fly out. Does anything change without it in here?

The shadow floats out of the mirror. Nothing inside seems to change.

Is it still crowded enough that one more person would be crammed and a second would just not fit, or does it now seem to have space for two more?

The size of the room has not changed. It's not really any less crowded after the shadow left because the shadow is tiny and flying.

Maybe it's just sized for eight and also wouldn't let in a ninth? Actually that would make sense, woudn't it. If the spell could hold only eight anyway, there's no reason to make the space larger, and if the shadow is taking up less space than average that would just leave more for everyone else.

She departs, and peeks into the other mirrors. Is there any variation, besides the occupants?

There's subtle differences in the positions of flowing silvery patterns deeper within the translucent walls. Nothing else seems different.

Maybe those are shapeable by the caster? There might be interesting art applications if so, but it could also be random.

Back to the wizard. "That's impressively smooth! What circle is it? Or are they magic items?"

"It's a second circle transmutation called mirror hideaway. When I cast it, the spell lasts around three hours. Almost tricks you into thinking it's a magic item."

This fits in a second circle slot? Really? "Impressive! Definitely useful if you go exploring, too. Can you move the mirror and take the contents with you?"

"You can't move the mirror more than about five feet or the spell ends. The mirror's contents are expelled out the front, in such a case."

"Oh well. Still, very useful!" It would have been nice to be able to carry around all her gear in a mirror without having to pay for a Bag of Holding, even if she should have the money for that now if she really wanted one. Not that she has second circle spells, or any reason to think she would have this one.

What about the polymorph spells demonstration? She wanders over in that direction. And if she gets distracted a time or two or three, that's not a problem, not as long as she makes it to the Breaching on time.