"Benedict," Betula calls into the cave, "I believe what you are looking for is hidden from normal sight. come here and I can lead you," turning to face the others, "and anyone else who wishes to enter into the regio. It is furnished."
"It depends on how tired I'll be when I'm done dealing with the ghost. And yes, I'm not sure I like the idea of going in there before sundown. How'd you do this in Intellego Vim? I would tend to do this in Intellego Imaginem, most likely."
Cath'rinne picks up the skull. "Don't judge me too harshly, bear-friend. I like to play with bones." she casts The Whole from the Part. If we're still in a magic aura of 4 in the cave, my spell roll is 28, so no stamina as this is a formulaic.
“One measures the astrological effects upon one’s body,” Betula says as if it is so simple, “I can demonstrate a similar spell if you are not too weary after you speak with the ghost.”
There is no aura in the cave, but the spell should still work. Cath'rinne sees, for her inner eye, a middle-aged woman.
Thinking about it, Betula will remember that there was a maga who had her sanctum in a cave. A follower of Verditius, she worked long hours in the lab and was rarely seen in the common rooms. Hence Betula did not really know her, and may have seen her only a few times before she left.
Do you all head into the regio?
Betula will lead whoever wishes to enter the Regio when they have finished their skull diggery. But she first warns them that this may be the sanctum of a Verditius maga whom she barely knows though she sees no sanctum marker either on this side of the Regio or visible from what she can see on the other and, like them, has no idea if that maga is still alive.
"I think I have her skull. I don't see a crime either way in entering an unmarked sanctum, nor in entering the sanctum of a dead magi."
She casts Whispers through the black gate before following Betula (this is an auto-cast without stamina cost in the 0 local aura). "What is your name and how did you die, follower of Verditius?" Unless the answer hints at possible troubles in the regio, she'll follow Betula.
Cath'rinne gets no answer; as the spell says (my emphasis),
You can speak through the barrier — the figurative “gate” — that stands between the dead and the living, to one corpse that has not yet decayed into a skeleton.
Some of you enter inside the regio. A dim light is shed from the ceiling which is draped with a tapestry. In the corner, there is a pillow full of black hair and smelling of cat. There a two small tables and enough benches and chairs to seat you all. The walls are smooth. There is no visible exit.
Those so adapt can roll second sight or magic sensitivity (I'll apply the aura bonus).
Benedict says, "I was really just looking for whatever was under that dirt." Then he realizes nobody can understand him, and he turns back into his human form, before repeating himself. "But I'd love to see what you can see." he says, and follows Betula into the regio. "An unmarked sanctum isn't a sanctum, but you should beware of traps or dangers." He is curious enough to want to see what's inside, but stays well behind the gifted Magi.
Betula does not see anything but the obvious. Cath'rinne and Benedict have joined her. Soon after comes the cat, who eyes you all suspiciously before it disappears once more.
Cath'rinne speaks to the cat in Latin. "Do you understand us? The familiar of the maga that lived here, perhaps? We may no harm."
Seeing the cat disappear she wonders if she missed anything previously with her more casual glance around the cave. Betula concentrates more fully on her mystical senses and looks around the cave again.
[OOC: Shooting for another Second Sight roll, stress this time, but feel free to just "let it ride" on the last roll made if you prefer.]
«Meow,» it says before it disappears without waiting for further remark. It is an Animal Ken+Perception 9+ to make any sense of its answer.
[Yes, @dc444, we let it ride. Try a spell. Or somebody else's skill instead.]
Thomas the cloth merchant stays outside the cave and keeps an eye out for anything suspicious.
Looking around and seeing nothing she didn't notice already, Betula turns to the others and shakes her head.
"Did the cat leave the way we came through?" Cath'rinne asks. She'll spont an InVi base 2, +1 touch spell to find out the level of the magical aura in the regio. This is a forceless casting requiring no stamina which succeeds unless the aura gives a penalty to spellcasting of 3 or higher. If the spell goes through but she doesn't find a magical aura, she'll check for a faerie one. She goes to examine the tapestry closer.
The cat entered and left at the same point where you entered (approximately, as precisely as you could tell). Whether it went the same way is impossible to tell when you do not see through the regio.
The regio is Magic Level 2.
Cath'rinne was asking her sodales to see if they know. 
Betula shrugs.
"There should be a lab here, shouldn't there be? Let's see if I can find the way..." Cath'rinne will take sometime to ceremonially cast Piercing through the Magic Veil. Rolled a 26 for a 13 result. The spell costs 1+2 Stamina from LLS. Assuming she does find another regio level, she'll point it to her sodales, so they can follow through as well.
The cat returns while Cath'rinne in deeply concentrated on her ceremonial spell. It meows loudly, and starts pacing arrogantly around the room. Those who pay attention (with a modicum of awareness/perception/animal ken) think that it smells and scrutinises each and every one of you, even if it pretends to ignore you.
It ends up with Cath'rinne to stroke itself against her leg. The casting not complete yet, it takes an easy (6+) concentration+stamina roll to avoid distraction.