The Magus would sink, but not get wet or dirty as the mud is a magical medium. The nature of water however is not solid so the magus would sink. A bridge can hold weight magic or otherwise and water can't.
I would say the rego terram effect, would move the ground but would do it without any force. This means the second the spell met resistance such as the head of the magus touching the roof, the spell would end.
A
First, I'd like to Thank you all for your input, it is helping me understand these spells a bit better, and I think there might be a little misunderstanding about what the spells are actually doing. the first spell is exactly what I stated, just turning the ground into water. It's not rushing at you, or trying to drown you, it's simply a body of water. I can easily bump duration to day, so by all means go swimming, if you can't swim, ohh well, spell doesn't really care that you drown. Now a Mage with parma up wont drown, but he sure can swim, or in this case, get dunked in. Ever get pushed into a swimming pool as a prank? same idea, i just created the pool under you instead. What makes this spell deadly in my hands is my ability to end the spell when I want. I'm not trying to drown you in it, but how well can you swim when the floor turns back into stone or dirt? Kind of sucks when your stuck in what is now mundane ground, and since there is no magic, parma no longer protects you from it. but again, the fact that I might choose to end the spell doesn't change the effect of the spell in the first place.
the second spell isns't so much as moving the ground up, its "Growing" with muto (Muto Terram pg 157 in ArM5, base 4 effect) and directed upwards with the rego requisite. I'll agree that if the spell was actually pushing the floor up, it wouldn't move as a whole because the mage is nailing it in place, kind of like how a latch will hold the hood of your car down. Depending on the force, it might rip apart if the floor is of poor quality. But this spell isn't pushing the floor up, it's growing the floor rapidly, and rego is just directng that motion upwards. By what's been explained, I'd agree that what's under the mage might not grow, but I dont see the rest of the floor stopping. I see it similar to nailing a sign to a tree. over time the tree still grows, and will grow around the sign.
I hope these explanaitions help out a bit more in understanding the spells.
I may be misunderstading your point about Prima Facia, but I don't believe it's breaking that rule. for a spell to affect "everything" withing a room, you would need to have prereq's for everything that might be in the room, animal, auram, aquam, terram, ignem etc. I don't believe that was the intent of "everything" however if your targeting wood, it would target all the wood within the room, chairs, tables, etc. so targetting the floor within the room shouldn't be a problem, I'm just effecting every inch of the floor, not just say the center blocks.
Hope the above explanation helps with what the spell is doing. How fast the room fills is another issue, but not what I am concerned with, just how it works with the mage present. By the looks of it, we're talking more of the balloon effect, it will surround the mage but never contact him, effectively entomeing him there. If he wasn't there, it would just fill that space and push everything else up to the ceiling.
Again I hope the explanation helps a bit. I don't care if he drowns or not, that's not what the spell is doing, it's just a body of water. the section of the book you quotes is what we call into question.Parma may keep the magical substance away, but that doesn't mean it still doesn't sink. So the question is; does he walk over the affected area or fall in? I would concede this, since he doesn't touch the water at all, if the water is perfectly stagnant, clear as glass, he would walk over it as nothing is pushing the water away from under him. But a simple ripple in the water, it's now in motion and now like it or not his own parma is keeping the water from refilling that space, forcing more ripples, causing him to fall in. Simple effect, as the ground is turned into water, it ripples. The deadly part isn't the spell itself, It's that I end the spell, trapping everything withing the floor.
As for my group being the ultimate authority, They're the one's who sent me here. Get some opinions on the whole thing 
thank you for the responce, as well as everyone else. And thanks ExarKun for the link. It actually helps alot.
I think I understand what your spells are intended to accomplish. In my reading of the rules, however, it is quite clear. Either you have to make a finesse targeting roll, or you have to defeat the target's parma. If the target is in a room and you target the room, you are going directly against his parma. If you don't want to go against his parma, you need to change the target category of the spell and make a finesse test to target him.
As for whether he sinks into the water, I think the answer to that is also quite clear from the quotation. Yes, he does (although he can swim in said water if he knows how). I'm not personally super happy about that, but the rules seem quite clear as Written.
As for whether he would be "entombed" by the volumetrically expanded floor, I think this also clear. Apriori, without any added magnitude for clever or controlled method of expansion, the entire volumetric expansion would simple stop immediately, because it could not move the magus on top of it and the base Muto Terram volume expansion effect only allows for uniform expansion. To expand in another pattern, or "like a gas" which is what you seem to want, would require either a much higher rego requirement and/or an additional auram requirement and in any event require SG/Troupe judgement to determine the precise magnitude shift required. Offhand, I'd guess +3 magnitude, going from the Rego Terram "highly unnatural fashion".
As for your end plan to cancel the effects and thereby do horrible things to the magus in question, I do not have the supplement from which those abilities derive, so I can't comment on that aspect 8).
Spell 1. There is a difference between suffocation and drowning. Parma prevents magical substance (eg earth muto'd to water) from entering the volume it protects so the water cannot enter the lungs - the mage cannot drown. Nor can he be crushed. However parma does not prevent the water from closing over his head if his head is below the surface level and it does not make the water air permeable nor does it obviate the mage's need for air - he can still suffocate even while the spell is ongoing. The effect of ending the spell is to turn the water back to solid earth which will make the mage unable to move barring inhuman strength severely cutting down his escape options. If he is deep enough and the earth is not rigid ie not rock there may also be crushing damage.
Spell 2. Does MuHe growth imply more plasticity than ReHe upthrust? Yes, especially if the spell description says so - again the mage will be closely but not crushingly entombed. I'd say a Rego requisite directing the growth specifically upwards would reduce the inconvenience - instead of the magus being enfolded (implying lateral growth) he'd be at the bottom of a mage shaped hole.
The presence of a resisting being within a room Target does not negate the whole effect, rather the being alone is unaffected.
Nothing I can add to the OP questions that havn't already been covered by others, but i noticed this
Just to point out, no you can't. The spell last until it's duration finishes. If you want it to end earlier, there are virtues and masteries in HoH:TL, or you can use another spell to dispel it. Possibly you already knew this, but i thought it best to mention it.
Duration: Concentration. You can stop concentrating whenever you like - in this case when the enemy's head is beneath the surface.
Quite true, also as a reminder, I am a Mercere, milvini magus, also known as a mutantes (HoH:TL, pg. 96-98). A muto specialist(why I avoided the post about perdo effects) with all the virtues that go with it. Duration effectively means nothing to me. Now if I could just get rid of my Avaricious(Vis) Flaw, the fun I could have with spells!
I believe that this approach is asking for trouble. Not the interpretation itself, but the approach that led to it. I just don't accept the premise to begin with that it can hurt him to begin with - not possible.
Here's how I see it... "we", as Players and SG's, don't understand Hermetic Theory. We rationalize it, we fake it, we simplify it into numbers. So, as a SG, I ignore any specific theoretical examples entirely, and only deal with the rare in-game example, and thus (hopefully) avoid getting trapped by any logic based on any ruling I've made but may later regret. How does it work, really? Just fine, it works just fine... and so does Parma.
What made Bonisagus' gift of Parma Magica so ground breaking was that it prevented magi from easily attacking each other. That premise, that 2 magi could meet and have a reasonable expectation of survival, was what allowed The Order to exist in the first place and flourish ever since. So, if it was that easy to circumvent, Parma would never have been that big of a deal - but it is (by definition and by culture).
So, any such attack may be partially successful, but for one reason or another (and those reasons may vary with the situation) a low-level attack can rarely (if ever?) directly* bring great harm to a mage without penetrating Parma.
(* Teleport a boulder high over a mage, and it drops as a mundane rock - that's valid. The stone-to-mud... not so much.)
Exactly - "something" may well happen, and the mage may find themselves in well over their head (figuratively as well as literally), but there will be ample time (and air) for the mage to react, or be rescued by anything more powerful than natural erosion. If they can get out before they starve to death, they're fine, even if it doesn't make perfect "modern" sense to do so.
But a Terram spell is not trying to affect the mage, who is Corpus/Mentem. Otherwise, any "Target:Room" spell would require an Aurum requisite (for the air) and an Ignem requisite (for the light), and so on. So while this is not a bad work-around to avoid harming the mage, it sets some very bad precedents for spell effects in general.
(One of the hardest things in Ars, and the reason that "canon" explanations are cherished by so many, is that the major contradictions and pardoxes have been resolved. Not all, not by a long shot, and not perfectly, but most, and usually well enough.)
This is totally not true. Invisible sling of vilano is the basic mage killer spell, level 10; since all it requires is a finesse (attack roll) vs dodge, and does mundane damage, this is generally easy to cause a wound to most magi who are not great with abilities.
Create vermin which auto generate (mundanely!) into water, let a magus drink, and let him catch a disease. No need to penetrate, easy spell. Rot the food. No need to penetrate, great chance of killing spree in the enemy covenant.
As for examples: they are valid. If you turn the earth in water, anybody, magic resistance or not, will fall and have to swim. When the water become earth again, it is no more magical, thus parma is just not helping.
The "re" transformation from earth to water is the "magic gone" process.
You may decide otherwise, but that's not what rules say.
As HoH:S points out (quite perceptively),
This balances those spells
Yes, but this is why the OP made his spells target:Room, to avoid having to make a finesse roll. If that were true, it would seem that mages would avoid buildings and structures of all types, as they would apriori defeat their magic resistance and leave them utterly vulnerable. This is why I believe Room targeted spells need to break the MR of any people in the room. Otherwise there are a million and one ways to target a room and kill any people inside it. My reading of the rules was that either you have to defeat their MR or you have to target with finesse (which I believe was designed that way on purpose for balance/lore reasons). Any scenario one concocts will necessarily end up falling into one of those two categories.
Is'n it actually stated somewhere in the core book? I thought it was mentaioned somewhere for healing spells (not rituals). I don't have the books here to check, though ...
Salvete
Widewitt
(p 113? That explains that Creo spells that "create" something can only target Individual or Group, so you can't "Creo Terram" a "room" worth of rocks or dirt. A healing spell does not fall into this restriction. Is that what you're thinking of?)
No, it doesn't work that way, but this is off topic. I'll start a new thread (here: viewtopic.php?f=4&t=7420 ) and this tangent can be discussed there.
d+5 is hardly a "mage killer", nor does it do "great harm". A disease is not an instant killer either, far from it. So I'm not sure what your argument is, here.
I know what the rules say, and said as much above. I have no problem with your interpretation of the RAW. But you're missing the point by only paying attention to that and ignoring the larger issue, that lies at the core of the game - The Order.
If it was that easy to get around Parma, magi would never have met peacefully, and The Order would never have been formed in the first place. So something more than just "what the rules say" has to be going on.
Because there is a Code, simply? Killing any magus is simple. Facing ten hoplites or the comrades avenging the death is not.
And since those indirect spell weren't known at the time of the Founders, but only a little later, it is an evolution which appeared when the Order already existed.
No. You are still missing the point.
Not because there is a Code, just the reverse. The Code is because there is a Parma - one that works.
Without an effective Parma, there would be no Order. Thus Parma has to work - and better than some narrow interpretations.
(If you still don't get it, sorry, I'm not able to explain it well enough, so you'll have to ask someone else. 3 strikes, I'm out.)
Cuchulainshound, I think you misunderstand ExarKun. Parma Magica doesn't need to be strong against Hermetic magic. It needs to be strong against non-Hermetic magic. Then we convince everyone to join and swear to the Code because we have a shield they can't handle because they don't have Hermetic magic. That Parma Magica is weak against Hermetic magic itself is irrelevant to the creation of the Code. Afterward it is the Code that holds you in check.
Chris
Callen uses better words than I could 
. He got exactly what I meant.
Mmm, I think I did, or at least I know what he wrote. Hermetic, non-Hermetic - what's the diff here?
If a low-level spell of any sort can slag a mage, then Parma isn't what it's described as. Non-Hermetic spells have an equiv in Hermetic terms - and so there's no diff "by the rules" - which is where he's coming from, by his own repeated statements. There was ample antagonism between magi who learned the system early on. (And I have a hard time believing that it took centuries to figure out the work-arounds .- if Bonisagus was a quarter the mage he's made out to be, he would have foreseen the problems. But there weren't any - so why should, how could there be now?)
I highly suggest looking at RoP:t, IHMRE, etc. You will find that their effects tend not to penetrate nearly as easily as Hermetic effects tend to. As for what the difference is, you're not using Hermetic magic until you join Bonisagus's Order of Hermes, so the whole convincing you to join thing and powerful defense you see is based on your non-Hermetic magic.
Consider Parma Magica 6 (professional level in an Ability) along with Form scores of 6 (a little above what is needed to train an apprentice). That's Magic Resistance of 36 and isn't so hard to achieve within 5-10 years of your gauntlet. How well can the other types of magic penetrate against this?
Chris
And pre-parma developing indirect attack spells was neither a priority (other mages didn't have significant magic resistance) nor easy (inventing spells without hermetic magic theory is hard work).
And the parma blocks the gift inspired spite - without the irrational dislike and distrust egging them on all the social and moral reasons that people don't murder each other despite being physically capable apply. (Most of the OoH are not PCs)