Will look at the character later, there are some things that might ask for a comment (although I see one that I thought did, probably doesn't 
)
Ok for terram, especially if you take a different direction, but you'll be stunted in advancement, we have no books.
I originally designed Tyrion with the "Stone Guardian" spell from Triamore (a 4th Ed ReTe 35 ritual), and thinking about trying to do some kind of statue version of Tireless Servant (ReCo 25 lesser enchantment). Looking at the rules for in-game spell development is sort of horrifying, compared to Verditus crafting. Even crafting the Stone Guardians as enchantments rather than spells, I'd only be able to churn 1/season out after I develop the text itself. Nowhere near the sort of 4/season production capacity I was imagining.
Plus, it seems like you guys have got a lot of Rego Terram in your group already. So I'm gonna play with numbers for a bit and see if there isn't a way to have my cake and eat some Mentem pie too.
I'll be offline for most of the weekend, and I'll be in Canada for the week surrounding Halloween. No idea what my internet access will be like, but I'll probably have it for at least a bit every day.
Regardless, character concept and my idea for the introduction won't change, and the current storyguide(s) can start working that in now: A covenant building/defense focused dwarf-blooded Verditus. Possibly captured by the forces currently besieging Ad Fons, who escapes with the help of a Faerie Friend (his fae father, a dwarf weaponsmith).
Since I'm going to be reworking his numbers, does anyone want to make suggestions for skills that a magus interested in covenant security would have?
Tatiana is high rego but her terram sucks and the terram expert in the new character thread really needs to be deleted. She didn't fit with the covenant and so was replaced.
Sorry, I was in a hurry before.
Welcome back, then! 
IIRC, fae don't have a precise language, but a pretense which allow them to appear to speak any language. I'm not sure, though, this is kind of fuzzy.
Anyway, even if this is wrong, given their human inclination, I think any language corresponding to your place of origin is right.
This is tricky.
I agree with ladyP that you're deleting stone, thus Perdo. But in a specific shape and by "crafting" instead of just making things worse, thus Rego. But you create stone wall where there may not have some, thus your Muto.
This'd suggest something like Pe(Re, Mu) Te, pretty complicated, unless you want it to be useless if there's not stone, thus Pe(Re)Te.
But I'm not sure if this is possible, unless the Entrance starts at your touch. Else, it'd all be happening outside of your perception. So "create a room, complete with an entrance or staircase, starting there", yes. But "at 10 feet behind earth, I'll create a secret room" feels wrong. I don't know if I'm clear. This poses no problem anyway, since I doubt very much you'll be willing to create a room you yourself can't access 
A possibility is to do it as craft magic, excavating the unused earth, in wich case Re(Mu)Te would work, but you'd have to roll finesse. This is probably the easier option. In fact, this should anyway require some Finesse for design, else the room may collapse (although the stone version could avoid or lessen that), unless there's a duration allowing Rego to keep the earth in place. The problems comes from the roof.
So, possibilities, quickly (I gotta go, so there may be errors):
Pe(Re)Te 15
Destroys and reshapes earth to create a room. This won't work on stone. Affects 10 individuals (about 100 cubic paces). Earth walls may collapse, depending on design and type of earth (average finesse ease factor 9, semi-skilled artist?).
Base 3, +1 req, + 1 magnitudes, +1 touch, +1 part. A higher duration means it just can't collapse during that time.
Pe(Re)Te 20
As above, but works on stone. Used on earth, it has earth walls. On stone, this is probably more solid, thus at least a lower ease factor.
Base 3, +1 req, + 1 magnitudes, +1 touch, +1 part, +1 to affect stone.
There's a problem here, as this'd work on only 10 cubic spaces of stone. Thus, either a cramped room, or you add an extra magnitude, for lvl 25
Pe(Re, Mu)Te 25.
As above, but, used on earth, it changes some to create more enduring stone walls. And there's the size problem when used on stone, although you could do multiple castings or to lvl 30.
ReTe 15
This is the Craft Magic route. How long would it take a mundane craftsman to do this? I don't know, but a season seems on the safe side. I'd say ease factor 9 (semi-skilled artist), +6 for season (= 15!!!) for a crude cave, with higher rolls creating a better, finer room. Very hard, and I'm not even sure the ease factor ain't too low 
Forget it.
Base 4, +1 touch, +1 part, +1 size.
I don't really know how to make this easy. Which is probably because it shouldn't
Just a note, as I ran into this problem when considering my future development: That guideline is for (totally) controlling Elementals, like there's also a lvl 5 guideline for controlling Disembodied spirits of (form) in TMRE p28.
Thus, just like TMRE's version wouldn't work on elementals (since they aren't disembodied), the reverse should hold true. Or else, why bother with "Coerce the Spirit of the Flame" (ReIg 20) when you could instead use Living Fire (ReIg20)?
Well...
On one side, I'm worried by the terram requisite, since it does nothing, save to impede you. You should have some minor benefit from it.
On the other side, although nothing in the guidelines precludes it, I don't like having a spell of similar or lower level that is actually better than an existing, published spell. This makes no sense to me. On the other side, you've got that "suitably prepared receptable" to compensate for the added flexibility (although this is mostly fluff, this is a lot better), as well as the requisite. Hey, that's the minor benefit!
What if the spell allowed you to take vis from corpses or other sources of raw vis, and to transfer it into into specially prepared faerie glassware, like little crystal spheres? And that, if you knew the Art of the vis, you could give them a specific color when casting the spell, in order to identify them better later?
Well, ardath at least really don't like faeries at all 
Well, he's got a Faerie Friend who is his father, and that implies he grew up nearby (else the flaw wouldn't yield much story). So what's the local language of the forests? Low German? Pomeranian?
Tangent: I spent two hours trying to look up the breeding history of the Pom Pom thanks to this game. Things were looking mighty interesting, too, when the trail stopped dead in the 1700s. Dammit. I blame you. I want those two hours back.
Okay, let's talk intentions and try designing the spell from there instead. What I want is a spell like Pit of the Grasping Earth, except that:
The 700 cubic foot space was an eyeballed estimate of how much space Grasping Earth created (I'm still not sure how big a "pace" is.). The smooth stone walls and stairway/arch aspects were unnecessary. I can just spont a ReTe after the fact for the same effect, and end up with a much more dwarf-like series of tunnels without it.
Your suggestion about the fae glass spheres (or, in my brain, "baubles") was exactly what I was thinking of. Really, I was just throwing in the Te pre-requisite to give a bit a color to the character. From Lady P's suggested revision of the spell, it sounds like there might be some game element to keeping vis in its original format that I'm unaware of.
With regard to your tireless servant only made of stone, I have this for a character in another game:
Stone Servant
Humanoid Statue size of Adolescent of a young girl.
Pawns: 16/16
Note: The pawns used is 16 for enchanted item with 5 powers. You would only need 4 for lesser item. (she has the lab cleaning spell from covenants, a defensive enchantment to keep her from getting stolen, and a few offensive powers)
That's what I tried to do, only to discover it was tricky as presented T-T
IMO, that is covered by T: Part. So no problem here. The only thing I'm not sure at all is if you wanted to create a closed hole, say, 3 feet underground without any "entrance", to a point you couldn't perceive at all. The range being the range to the part of the spell you can perceive. Like, you must burrow, beginning somewhere on the ground, which is your "entrance".
Sure, no problem, that's what finesse is for, too. Note that, at ground level, you wouldn't need to worry about the roof caving in (it's just a hole), so you'd get something just like Pit of the Gaping Earth.
Btw, I just realized I wrote bullocks in my previous spells: Muto only works for the duration of the spell.
More on this... when I can
Any one with an idea on how to get our new magus into the game? I am thinking a strange ReCo botch...
Curiosity or seeking a place to blend since we have a lot of faerie blooded that aren't merinita. Thus a covenant that a fae blooded mage might fit in the best.
I was thinking it might be cool to somehow integrate me into the current plotline. Maybe my faerie friend/father is a political opponent to the Goblin King? Or perhaps I'm working for the fae forces at the gate due to some kind of bargain which I need to obey the letter of, while trying to oppose the spirit of the agreement.
Alternately, Tyrion is very interested in covenant defense magics, and may have been directed to Ad Fons by a person/group in the Rhine that wants to make sure they don't switch tribunals.
Any other ideas?
The only problem I have is that you are going to enter a covenant that is under siege. The reason for being there is your own to decide. I want you in the current plotline so if no one objects then just start writing a post on how you enter the covenant despite the siege. Either you snuck through (with great luck) or just happened to land there by a ReCo botch. Your choice.
You also need to give thought as to how you are going to avoid suspcion and paranoia when you arrive. Mariella is a bit paranoid at the best of times and this is not that, further she actualy beleives that this attack is linked to enemies within the order so her panaoia will be in overdrive concerning new arrivals.
Arriving with letter of recommendation from somewhere in the Rhine tribunal would go over a lot better than a botch or just showing up. My first character left because of how quick this covenant is to attack, imprison and kill strange mages.
Amul write your way into the story, if nothing better just come running from the forest with goblins at your heels.
Can I have a few shield grogs with me?
Ok, take a few.
I am realizing that one of Tatiana's flaws really doesn't fit her. She is more wrathful than compassionate. I am trying to have her show compassion but we are in the middle of a war for survival and is pretty much destroying it. It is a good all out or die herself situation.
I don't want to fill the IC thread with OOC. Tatiana has never had any contact with Occultis. She is a Novgorod Ex Misc tradition that came here.
Well, she seems wrathfull most of the time, although less so than mariella 
Yet, even in war, one can show compassion. Let me tell you an old Star Wars RPG exemple: In it, the sith, being cruel and wicked, dealt damage with their laser swords, which could kill people without them having the time to realize it. Meanwhile, the jedi, being on the light side and all, had the choice: Instead of swiftly killing an opponent, they could instead maim greviously him, crippling their opponent for the rest of their lives.
Hum... Bad exemple... :lol
But you get the idea. Note also that you can reserve your compassion for humans. We had some wounded too, and Tatiana could take care of them, and trying to protect our soldiers to the best of her ability.
Oh, and Ardath comes from Novgorod too
Mariella amd Justus (aliong with several now departed mages) visitied it in the very first story thread to purchase some books(not sure if we got the books from there or Durenmar in the end). I beleive Ardeth stayed at the covenant