The rules on Magical Senses (pp. 113-114) mention the need to penetrate, but I assume that applies only if the sense is the medium for detecting something within the person of a creature with Magic Resistance--it shouldn't apply to species emitted by that creature. (The creature is magical, but I'm not sure the species emitted are themselves magical--and that seems to be the consensus: Imaginem and Resistance)
So, an InIm spell to enhance hearing is base 1, +3 for target Vision, +2 for duration Sun, and let's give it a +1 for complexity, in that we only want to make it easier to hear crying (not, say, the storm). That's a level 15. Viola's casting total (with Potent Spontaneous Magic) is In 8 * 2 + Im 8 +2 Sta + Aura 6 = 32 + a stress die, all divided by 2. She couldn't quite manage it without Fatigue, due to the need to double one Art and/or add the stress die..
Die roll: 8, with a Weird Magic roll of 5.
How's the storm coming? We don't want to proceed until it's started to get dark. The need to rest for a couple of minutes to recover the Fatigue provides a convenient excuse to delay a little longer.
Right now, the sky is overcast, but Viola suspects that it's not going to get truly stormy until you're in the final level of the regio - with fae, these things tend to progress narratively rather than with strict attention to time passed.
I'm a bit unsure exactly what you're aiming for with the spell - something that enables you to see auditory species?
Vision is also +4 rather than +3 - do you actually mean Range: Sight? If you do, there's the problem of what you're targetting - Imaginem is more of a constant stream than a discrete object at the time of casting.
Thinking about it more, it feels like what you need (and possibly were going for?) is a variant of Eyes of the Eagle (pg 145 of the corebook) that affects hearing rather sight? If so, I think that would be built as Base 3 + 2 Sun + 3 Hearing ( +1 complexity for targetting crying only) = 25.
Sorry, target should have been Hearing (equivalent to Structure). She wants improved hearing, but only for crying. Yes, I was using Eyes of the Eagle as a model, but no, I didn't notice the similar-looking base 1 and base 3 effects. However, I don't think the base 1 helps, even if we could find a proper target, because it doesn't enhance the sense. MuCo could probably enhance her hearing, but not selectively.
We could drop it to Conc, and she could just about manage a level 20, esp. by adding the +2 for booming voice and exaggerated gestures, but there's no telling how long she can maintain the Conc. What would be the ease factor for concentrating while resting and then while walking? I'd think the walking concentration would be easier than normal because she's concentrating on the noise she's following.
The maximum amount of time you can concentrate on a spell is 15 minutes per level of concentration. Viola has Concentration 2 (spells), so that would be 45 minutes.
That assumes she's not being sidetracked, which she almost certainly is. Walking is only a Base 3 concentration roll; however, navigating through a maze is likely to be harder than that. However, I'd be happy to say that "concentrating on honing in on the noise" was something she could do without requiring concentration rolls, as it's the purpose of the spell (pg 82: "Note that if a spell is designed to let the maga do something, doing that thing does not interfere with concentrating on the spell.")
Anything else, e.g. talking or casting spells, would require concentration rolls in line with the table on page 82 of the corebook.
In theory she could cast Maintaining the Demanding Spell, but she doesn't know it and it think ends up net worse off if she does (although it might be possible to recover the fatigue more quickly splitting it over two castings).
We'll just keep concentrating. Things shouldn't be too distracting until we get close to Halia (Viola will try to let Calliope talk to the fae until then), at which point the spell might well not be needed.
[Okay - note that Viola is down one fatigue level until she gets a chance to rest (which she won't be able to do whilst concentrating).]
The group passes on through the waterfall and down the stairs to Viola's lab. There they ignore the door to the crones and instead pass down the next set of stairs into the second regio level.
Here the corridor formed by the stalagmites is open to the sky - which means you have no protection from the rain that has started bucketing down. Calliope rapidly casts a Rego Aquam spell and then stands only mildly damp whilst everyone else not taking preventative action is soaked to the skin. A massive peal of thunder follows just a moment after a terrific flash of lightning, causing Chryse to clutch on to Viola; the resulting jostling causes a moment's flicker in Viola's concentration but she is able to successfully maintain her focus on the spell.
In the distance through the storm, Viola can hear a woman's voice crying - it sounds as though it is as yet some distance away.
[OOC: make concentration rolls for anything further Viola wants to say, please - EF 12 for a couple of words, EF15 for a full blown conversation.]
Viola sets off down the stalagmite corridor, which soon divides and divides again. Following the sound is made more difficult by the absence of a clear route to her goal; some of the passageways that seem to head in the right direction soon double back on themselves. Despite this she is able to make progress in what is at least more or less the right direction. As she does so the wind begins to pick up until it is becoming difficult for Chryse to walk against and even Viola is beginning to have trouble - and it's clear it's still building.
[OOC: At this point walking into the wind requires a Size + Strength roll against EF 0. Chyrse is at -7+ die, Viola at -4 + die and Calliope at -3 + die. Other characters can be assumed to be making the roll without difficulty at this point.
In addition to this, Viola should make an EF 9 concentration roll to keep up her spell against the buffeting of the wind.]
How loud is the crying? Might she be able to hear it without the spell? She's thinking we might need to ReAu if we're going to make any progress, esp. without leaving Chryse.
The storm is not a great place to rest, but Viola can have a conference with Calliope, talking loudly to be heard over the sound of the wind and drumming rain. Unfortunately Calliope has no knowledge of Auram. She does know some Rego, but even in this aura she'd be doing very well to cast as much as a second magnitude Rego Auram spell.
[OOC: Ouch, a negative Stamina really hurts. Right now the wind is around the boundary of a normal and severe weather phenomenon. You're clearly going to need the Base 5 guideline to ward against a Severe Weather phenomenon, and possibly even the level 10 guideline for a very severe phenomenon if it keeps getting worse.]
Calliope does consider whether she can take over the Intellego Imaginem spell for Viola, Imaginem being her area of speciality, but reluctantly concludes she's not going to be able to manage that either.
One minor positive is that the storm doesn't appear to be getting noticably worse whilst you pause, although there's no sign of it letting up either.
If you make that ward Touch, Group, and Sun, you're already at level 25. However...if we can't ward the group, we can control the wind ("one wind" is an Ind target in the Auram guidelines). It's the same base 5, and at Touch, Ind, and Sun, it's a level 20. We're not going to eliminate it entirely, since it's part of the story--just reduce it from disabling to annoying.
So here goes:
Re 9 + 2 * Au 5 +2 Sta + Aura 6 + Loud Words 1 + Exaggerated Gestures 1 = 29
That's ugly, but Viola doesn't see a better path, so let's use Life-linked Spontaneous Magic and roll a die:
3; Weird Magic is a 1.
That produces an effect level of 16, which is nearly a magnitude short, so she loses 2 levels of Fatigue, going from Winded to Tired. After that, assuming Viola can now rest, she's going to wait hear as long as the creek faeries tolerate it and Halia doesn't show up--the full 42 minutes if possible--and then cast the InIm effect again. If she can't rest...I'll need to think of something else, because losing yet another Fatigue level is getting dangerous.
I note that when your secondary Art is less than 10, you're actually potentially better off using your fatigue on LLSM than on getting to add the Art a second time, although the way the magnitude boundaries fall in this instance means it doesn't make any difference. (Plus I suppose the risk of accidentally killing yourself goes down if you're not using LLSM).
Viola thinks her spell will work as long as she remains in the current "corridor", but that once she moves past the next junction there's a good chance she'll be dealing with a different wind.
Once it becomes clear that Viola intends to stop for a while, Calliope directs the grogs (@ironboundtome) to use their cloaks to contruct a shelter, which she then intends to casts Cloak of the Duck's Feathers on to make semi-waterproof.
LLSM only works with a fatiguing spont (it's at the start of the second paragraph, at the top of the page, but it's an off-hand mention, probably not the best way of writing it into the rule).
Stopping to rest, after casting the spell, will also give her a chance to think...which she needs, because I'm out of good ideas for the moment. Aside from not wanting to leave Chryse behind, Viola is afraid those strength rolls are going to be too much for her and Calliope, esp. if she's got to concentrate in the meantime.
I think, once she's rested, she going to try another spont to call out to Halia. But I'm going to put a pin in it until tomorrow.
What Viola wants to do is to make her voice very loud long enough to say, "Halia, your children have come to you."
That should be a ReIm effect (annoying, since the ReIm guidelines are pretty much all for sight), though since we're talking about unnatural loudness, it might be MuIm, with a base of 1, and maybe a magnitude or two extra for making it really loud. Range is Pers, Duration is Mom, Target is Ind, so actually, whether it's ReIm or MuIm it should be pretty trivial.
For ReIm (the worse case), her casting total is Re 9 + Im 8 +2 Sta + Aura 6 + 1 for Loud Words (it would almost seem wrong not to) +1 for Exaggerated Gestures = 27, which is a level 5 without Fatigue, or a level 10 without Fatigue and rolling a stress die (Innate Spontaneous Magic) --should be enough, so let's do that.
Here's the stress die just in case:
3, Weird Magic 1
After that, cast the hearing spell again:
6, Weird Magic 6
[I think Rego would be to move it, rather than to make it "bigger". Muto (or possibly Creo if making entirely new sounds rather than changing existing ones) with extra magnitudes for making it louder feels right - standard "size" would only get it up to the volume a person could get to, whereas extra magnitudes would boost it to 10x or 100x.]
Viola's voice sounds almost unbearably loud to her, although her companions seem largely unaffected - they've heard what she said, but not with the same deafening force. None the less, anyone in the area will have heard what she said - as made apparent by the minor earthquake which throws many of the party to the floor.
[Make a Per + Awareness roll.]
After picking herself up, Calliope suggests: "Well, she'll know we're here, but I don't know how much better she'll be able to travel than we can. Demeter?"
I assume the "Alertness" specialization to Awareness applies here. That makes it:
Awareness 1 + 1 for specialization +2 Per + stress die 6 = 10
Demeter had us a making a brew, didn't she. Viola will presumably be carrying it--she'll ask Calliope about the wisdom of this course, but her thought is: as the children and mother approach, offer the brew to them, starting with Halia, to celebrate the occasion. For what it's worth, a Faerie Lore roll for that:
Faerie Lore 4 +4 Int + stress die 0 = 8; potential botch rolls are 2, 3, 6, 0.
Calliope sighs. "Maybe I should have kept the bit about Demeter transforming the storm into nourishing rain in the song. It may not have worked anyway, though - going directly up against Poseidon's power in an area of his speciality in a place aligned to him would have been a significant request."
"I think the big potential issue is if she turns us all to stone first - we won't be safe from her until after she's drunk it."
Ipek meanwhile, alongside blatantly eavesdropping, appears to be poking one of the stalagmites that make up the corridor walls. Seeing Viola notice her, she remarks "I think that tremor weakened the maze - this rock has little cracks in it now."