Alexei thought Wilhelm was the expert...
To clarify: no one has seen beyond the regio boundary. How can there be a map of something no one has seen?
The Inexorable Search, like all Intellego magics, doesn't work across realm boundaries. She wasn't casting it to try to locate him inside the regio; she has more than enough MT to know that wouldn't work from outside, map or no. She was casting it here, with either a genuine or a ghettofied map of the area, to see if it would locate him in the mundane world.
Just because he was last seen at a regio entrance doesn't mean he's necessarily in it now. Occam's Razor, sure, but always eliminate other possibilities when you can, because in science, a confirmed "no" is better than an unconfirmed "yes." Jonathan and Arya both know Fieltarn is inside the regio, but Laetitia always crosses her T's and dots her i's.
Right, doesn't work across realm boundaries (with an additional qualifier that I'm adding) if you're in a separate realm. If it's a boundary of the same realm it might work! You're making certain assumptions that don't fit, but I have perfect knowledge here. Shortcutting a bit, once you cross into the ruined temple, you actually move directly into a regio, but the boundary is easily crossed at this first level. Second sight doesn't pick it up easily, because it is very faint and everything appears normal. It requires A LOT of concentration to pick up the slight change, and it was easier for Laetitia to detect the close tent flap boundary. Yes, I've made an assumption that Inexorable Search was done inside the ruined temple.
I wanted to be finished with this quickly, and not drag it out. This is dragging out longer than I would've liked at a point where I certainly don't want it to. My desire was/is to wrap this story up. I've given permission to the participants to contrive a method for transferring knowledge and clues already within this thread from the player to their character. How that happens is an exercise for the player. There is enoguh information within the thread to figure that out. If a player isn't sure, they can ask me directly. If you're playing your character as if they aren't sure, stop and make them sure.
So, while this may be fun for the character/player to test out possibilities, be advised that I am not finding it fun and wish to move this along. If you want to RP a comdey of errors trying to figure this out, go ahead, I'll unsub this thread, just alert me when you're ready to proceed. And if my tone is harsh, apologies, lack of sleep, hard work at home and at work are making me cranky. You've been warned. 
Having read through the whole thread twice I didn't catch at all that there were two separate entrances. (Problem with red herring is, sometimes we eat them.)
We go in and scout around, if we don't see any sign of him then after we've made a sweep of that level, I'll sketch out a rough map in the dirt, and cast tIS again.
And have made note of any other entrances to deeper levels, and rinse/lather/repeat there if need be, ad infinitum, until he's found or we run out of regio levels.
tl;dr I press the Solve the Adventure button.
It's not that there are separate entrances to the regio. Entering the temple actually puts you into the regio. And then within that regio you see what looks like a closed tent flap that leads to a higher level. The initial entry to the regio is not illusory and so doesn't trip second sight unless one really concentrates, and it's open to anyone who steps across the threshold into the temple.
The problem with going through the tent flap looking opening is the one that needs to be solved.
And you can't press that button, only I can. 
Regio entrances don't need to be "illusory" for Second Sight to apply. They're not naturally visible; SS doesn't pick them up if they're also illusions, it picks them up because they're specifically included in the ability description.
So, either Second Sight works (and you've implied it should - given the description on p. 189, if you make the "Regio Sight Roll" you can cross it, seems pretty obvious to me that if you fail that roll, the reason you can't cross it is because you can't see it; it's called REGIO SIGHT ROLL ffs), or we have to try to recreate the conditions under which Fieltarn went in.
My SS check is a 9 + 3 Per + 3 Second Sight + 1/2 the magic aura 10 = 20. So if this regio can be entered without having to follow a particular ritual, then Laetitia can almost assuredly cross the boundary as long as the next level is still Magic.
If this regio boundary can only be crossed by a certain ritual (or if the aura on the next level is Magic 18 or greater-- in which case I'm installing a lab there, btw), your description that it looks like a tent flap implies that the "ritual" is to lift the flap. That doesn't work. So trying to deduce the ritual/path by recreating the conditions that let Fieltarn in, are pretty much impossible for Laetitia. There's no wolves to be negotiate with, if they're a necessary guide, and if the entrance will only "open" for four-legged creatures, Laetitia is deficient in Muto, and while Alexei doesn't have that problem, he's not my character.
So if it's not fun for you to watch me bashing my head against a brick wall, maybe consider it's not fun for me to bash my head against a brick wall. Which isn't even working the way brick walls are explicitly described in the CRB.
I opened this story to anyone. People put their characters in, or didn't. It is conceivable that the right mix of characters isn't here to solve this. If that's the case, I expect the characters to sort this out without my involvement. I don't need to be here to facilitate PC interaction. I think it was pretty clear from a player point of view that the character transformed into a wolf and appeared to cross into a regio.
If your second sight reveals an image that is identical to regular sight might it be difficult to tell that there is a boundary?
I'm not sure what total you're trying to do here. Your Roll would be Per + Ability + Die, so in this case 9+3+3=15. That would have to check against an ease factor of 5+(2xdiff) The diff is diff between current level and the next level. If say the regio level you're in now is 1, and you can go directly to Fieltarn that diff would be 9 and therefore the ease factor would be 5+18=23, well above your 15. This presumes that one can cross directly from here to where Fieltarn is.
This presumes that I knew you were bashing your head against a wall, and that there aren't other players working in this thread... Neither of which is true.
Nope, sorry. If that were the case, naturally invisible things would remain invisible to Second Sight, because they "look just like nothing."
I added half the magnitude of the Magic Aura, because it's a Faerie supernatural ability.
Since Laetitia's Second Sight is a result of Strong Faerie Blood, the Second Sight is a Faerie ability, and thus only receives half the benefit of a Magic aura. So the roll is 9+3+3+(10/2)=20.
Well, consider yourself informed that this whole thread, since "Yeah, let's go with that" has had me scratching my head and going "wtf?!?" pretty constantly. The thing I'm pretty good at that is supposed to work and SHOULD work (because if it doesn't work, I shouldn't be able to see the gorram 'tent flap' at all) doesn't, so instead I'm just spinning my wheels and doing whatever I can to try and eliminate possibilities.
If you're suggesting Laetitia just march home and say "I give up, someone else do it because clearly this adventure is optimized for some other PC" I'm not going to have my character do something totally out of character just because it's not fun for you or me in the metagame, so let's just say Laetitia continues to bash her head against the brick wall, without any guidance from you or me. But here, let's try being really blatant about something I'd been subtle about earlier, since Alexei doesn't do subtle, and perhaps qcipher doesn't either:
"Gee. It's a shame that I really hate Muto. Because the next thing I would logically try would be to take the shape of a wolf and try to nose my way into this little spot right here. It's really too bad we don't know anyone who can shapeshift into a wolf. Hey Alexei, I BET YOU COULD DO IT, IF ONLY THERE WERE A REALLY STRONG MAGIC AURA HERE."
Better?
Well, the aura here is 1, not 10, as I alluded to. Therefore the bonus is .5. 9+3+3+.5=15.5, which would be 16.
I''ve been doing that since the segque back to the cottage. Keep in mind that with the exception of setting everything back on course that I've keep things very terse because I haven't had a lot of time. I may not have been descriptive as I should've been, and I apologize for that.
So, let's cut to the chase. If you want to access the next level of the regio, you need to find someone who can transform into a wolf. How that's handled is a determination I leave up to the players and to act out as much as necessary. I'm not handing out 10 pawns of Creo vis for free. There is some cost, and there's more work to be done even after going to the next level. And then there's figuring out how to get back down, where Fieltarn is currently stuck at.
Is this fair?
Looked like it was 10 inside the temple, or at least it was when Fieltarn was here.
I don't care about the vis. My character cares about finding and helping someone who may be in trouble. I'd be perfectly okay with you waving your hand and saying "You guys find Fieltarn and bring him back to safety but you don't find any vis."
If the aura here is only 1 then Alexei has very little chance of pulling off the MuCoAn here.
Laetitia says "BRB ok", grabs a rock or twig off the ground outside the temple, pops back to the covenant and asks Fiona if being a "Daughter of Circe" means she can transform other people into animals, because if so hey we need you over here plzkthx, but I'd prefer you turn us all into wolves rather pigs, not the least reason of which being that pigs could reasonably be eaten by the wolves on the other side.
Yeah, and I said there were no exits from the temple, except for what appeared to be the remnants of a regio boundary to his second sight. Left unsaid there is that the temple where he is is not ruined, like it is where Laetitia et. al. are.
This is something that Brionne would know, as indeed he has been transformed into a wolf. I expected qcipher (stern look) to offer that.
I...I...
Well, I just read this now, so I couldn't really offer something until now. But Brionne helpfully adds (in earshot of Latitia):
"This reminds me of the Winter that I served for Fiona Master Alexei." Alexei groans at that, before Brionne hastily adds. "No, no! What I meant was when she changed me into a wolf to scout after the missing sheep. Maybe as a wolf I could sniff out Fieltarn's trail?"
Boy, y'all have been busy today.
Yes, Wilhelm does have some Area Knowledge of Bibracte, but it doesn't seem like we need him to draw up a quick map of the area after all, since we're inside the first level of the regio. If he does, his Area Knowledge roll is: Int 0 + Area Knowledge: Bibracte 1 + die roll of 4 = 5. If this counts as Woodlands and he gets his Ways of the Forest bonus, then that could jack it up to 9 (+1 for the specialty, +3 for WofF). His roll for drawing the map in the dirt is: Dex 2 + Craft: Drawing Stuff in the Dirt 0 + die roll of 4 = 4, 7 if he gets Ways of the Forest.
Yes, Fiona does have Shape of the Woodland Prowler, which she can cast without words and gestures. The thing I don't like about that spell, and why I designed Taking the Raven's Wing the way I did, is that (as I read it) you can only cast that spell as many times as you have wolf-pelts available to use, and she just has the one pelt. If it would work with any ol' wolf pelt and if we have more laying around somewhere, then she'll grab those. And, unfortunately, she can't Spont it because her Spontaneous Magic sucks stinky monkey butt.
So, yes, Laetitia can bibbiby-bobbity-boo back to the covenant and get Fiona...who is going to have to hoof it to the temple, as she has no travel spells and I'm not sure Laetitia can pull off a travel spell on Fiona at her size.
Nope, she can barely cast it herself, BUT, she can summon a horse that will bear her, Gift and all.
"So Latitia, we need to be in wolf form to cross this Regio then? Well I suppose Fieltarn is the one for that, perhaps using some vis I might be able to pull it off spontaneously...but the potential mishap is likely not worth it. Who will be receiving Fiona's spell then?" Brionne lights up at the question.
I always hated that bit in the spell description too, because there's no such requirement in the description of the spell guidelines, and it's inconsistent with Curse of Circe, which has the same base level but doesn't have a requirement for a "pig pelt" and doesn't have any magnitudes added for being an exception to the pelt thing. I think someone threw it in for flavour without realizing it was stupid.
But from the description, yeah, it sounds like any wolf pelt will do.
She clears her throat. "Actually, it's pronounced 'lye-TEE-tee-ah, not "luh-TEESH-uh"; it's spelled with a dipthong-- it is Latin, you know. I hate how English magi will refer to a Roman Emperor as "SEEZ-ur" even though they're fluent in Latin and know bloody well it's pronounced KAI-sar; don't you as well?" She frets a moment then, wondering was that too subtle for Captain Oblivious? Should I just blurt out that I may have to slap him if he mispronounces my name one more time? I suppose I could always hire a Latin tutor for him; most apprentices command the language better than this grown magus. Well, everyone must have his talent, and stick with it. She sighs and moves on.
"As for the requirement of entering this regio boundary, I don't know whether a wolf shape will assist or not. I simply think it best to be thorough, and when Fieltarn entered, he was wearing the shape of a wolf. If that does not work, then next I will likely try the more platitudinous routes-- like finding some poor beast and killing it here in the temple, though I shall be quite put out if the magical pagan entity within is so... pedestrian."
(If I can get Fiona to make a skinchanger cloak for me, I think I want to put my lab inside :p)
There's an almost perceptible drop in atmosphere as Alexei's pronunciation is mocked, at the sight of his expression the grogs with him become a bit tense as well. He scowls for a moment while stroking his beard before speaking.
"A pity that the Flambeau with the better pronunciation was busier than myself...I was only in the middle of working on my Talisman. Perhaps he could have accompanied you, Lye-TEE-tee-ah." he sighs and checks his spear tip. "Let's get this over with, shall we?" much of his mirth and exuberance for helping out on this seems to have faded.
((It doesn't take much to realize he bit his tongue quite a bit there.))
...Which is great, because Laetitia is now quietly exulting to herself, He can be taught! HE CAN BE TAUGHT!!! O frabjous day!
As soon as Alexei says her name properly, she bounces up and kisses him full on the lips... And then goes along as though it never happened. (Positive reinforcement and whatnot :p)