Arts are redundant with one another (Ice magic)

In another thread the subject of ice magic came up. While there is a statement in the core book regarding solidity being a terram thing and water being an aquam thing, I think it's not frequently applicable.

The arts are the creation of humans they've been re-engineered by humans, as seen in the expansion of the vim form in legends of Hermes. It's easiest to run a game and say the answer to the question which art covers ice is that the question is in error in presuming that it's one art. There's nothing the least bit contradictory in having more than one art being able to manipulate a thing. Rego vim and Rego Herbam can both stop wood faeries, Creo Aquam and Creo Terram can both make ice walls.

Anyone see an advantage in running it differently?

If you wish to invoke pure ice, you require Aquam.

If you wish to solidify already existing water, you may use PeIg.

I rule it saying solid water specifically is a special use of Aquam, as it is stated in Aquam. The part in Terram about solid things simply exist for other Form Arts which are incomplete ones. For example there are not discoveries and spells about solid Auram, hence a CrAu(Te) could manage it.

But it looks like there have been enough Magi specializing in Aquam during the past centuries, so that solid water already is a part of the basic Aquam guidelines.

I’m happy with multiple Form Tech combinations applying to different aspects of Ice. I agree it is imperfect but I like that imperfection as both a demonstration of how Hermetic magic is not perfect, and also because I really like the idea of secondary elements much like secondary colours.
Lava is another substance which has a compound set of applicable forms and techniques depending on the effect.
I wrote up an Ice focused magus in a game and found that it was far more complex than just choosing something like steel, however the frustration and complexity was a feature.

I was just about to mention Lava, but ironboundtome beat me to it.

Elemental Magic's ability to ignore requisites and/or a Magical Foci are really helpful here.

I'm inclined to generally give it to Aquam over Terram generally, with a fairly common Rego requisite for spells involving ice, as Rego Aquam 3 is "change water into ice". I'd probably allow MuTe(Aq) base 3 to turn dirt into ice.

Cr(Re)Aq - Making ice spears, walls, etc from nothing.
ReAq - Taking some of the water from a river and making it into a bridge of ice.
MuTe(Aq) - Changing a wall of stone into a wall of ice.
PeTe(Aq) OR PeAq(Te) - Demolishing a wall of ice.
ReAq - Moving blocks of ice around.

PeIg or ReIg create Ice from water, just as CrAu or ReAu can accelerate wind. Multiple ways to solve problems, scare locals, and violate the Code is cooler.
Edit: or CrAu, CrIg, or ReAq to create steam. Thinking about that a minor focus in steam would have limited applications and a variety of Arts. Might be a good challenge.

Yes, that's the text box on page 79, but why would that make a better game?

I'm not suggesting, for the most part, that different aspects of ice be in different technique and form combinations. I'm suggesting that the same aspects of ice can be in different technique and form combinations.

I don't see this as an imperfection any more than being able to loosen a bolt with a wrench or a ratchet is an imperfection in my toolbox.

I think there are different questions entangled here.

The first is: can I achieve roughly the same end result with different Arts? The answer is, often enough, yes. I can turn water into ice via PeIg, or via ReAq, for example. I can collect together a hundred thousand seeds dispersed on a field via ReHe, or via Cr(Re)An - making little critters that will collect them for me. And so on. However, these end results all come into being through different "paths", so to speak: they are conceptually different effects (e.g. removing heat so the water naturally freezes into ice, vs. turning it directly into ice).

A subtly different question is then: can I use different Arts to get there through the same "path"? Generally, I'd say no. The idea being that each effect should fall into the "most reasonable" TeFo combination; and each object should fall into the "most reasonable" Form, even though different parts of it can end up into multiple forms. Negating this creates a lot of difficulties in aspects of Ars Magica far beyond Hermetic spellcasting: non-Hermetic supernatural Arts, Form resistance, Magic Realm affiliations etc.

One exception would be this: a more general spell with the appropriate requisites can usually take the same "path" of a more specific spell - e.g. a ReTe(He) can move stuff one would be able to move with ReHe. But a ReTe spell without (at least casting) requisites can't move stuff that you would be able to move with ReHe, except through a different "path" (pushing the metal lid of a wooden box, for example).

Yay, my Aquam/ice specialist in my current game is about to marginally increase his usefulness!

Seriously--of all ten Forms, Aquam seems to be the least applicable and useful. You can certainly come up with creative uses here and there, but it doesn't have the immediate applicability of say, Terram or Imaginem.

Though I did get to say 'Boatdoken' a couple sessions ago, so that was definitely a high... forgive me.... a high water mark!

I argue PeIg cannot create ice if only one form can create ice. This would be like using Perdo Corpus to cure a disease or remove a tumour. It may make sense to the modern mind, however it runs contrary to the setting and much of the game.

I also refer to Classical elements often and insert effects that seem to be missing in Aquam, Auram, and Terrem which are in Ignem. I find Ignem as written to be problematic in that it seems to be the special form which deviates a bit from Aristotelian physics and inconsistent with the rules other forms need to obey.

For instance PeIg can chill a person draining a fatigue without a Corpus req. Even though heat is a quality of the body, one’s inner fire may be Ignem, however the target being affected is Corpus.

Contrast this with PeAq used to dehydrate someone, which has a Corpus requirement based upon the very notion above.

Perdo Ignem to make ice I find problematic also because Perdo cannot sharpen a sword, it makes a thing worse. While ruining something’s heat source will make it get cold, if you’re making ice, heat is a quality of the water and is Aquam. And Ice forming a solid instead of a slush is a more perfect form of Aquam, Creo. Perdo also destroys all of a quality being destroyed, not part. So Perdo Ignem to destroy a fire’s ability to burn does so wholely, one cannot partially destroy its ability to burn such the fire will not burn cloth, but burn other things.

The mistake (in the RAW) I think is in the idea that Ignem governs Heat and Light as well as Fire. I don’t think it should, at least not uniquely. Hot is a quality of Fire. Hot is a quality of Air. Cold is a quality of Aquam and Terrem. Heat is a quality of other forms, it shouldn’t be a form itself.

Instead of trying to fix things by removing base effects from Ignem or adding requirements to existing spells, I find it better to simply add effects to other forms and remove the requirements where it makes sense.

Also Ignem is just too good and I find it upsets game balance.

Or maybe heat is not a part of the body and is something of its own within the person, thus not needing a Corpus requisite. Compare this to Black Whisper (PeMe 40), which does not need a Corpus requisite to affect a person's mind or an Animal requisite to affect a dragon's mind, for instance. Consider that outside of Ignem there are two different approaches. Ignem has been written to affect people and things more akin to how Mentem does than how Aquam does.

Seriously? I consider Ignem to be a weak Form. I'm not saying Aquam is one of the strongest. But I certainly don't consider Ignem to be too good. If you want to examine this, we can start up a new thread.

The mind isn’t a quality of the body.

And if Ignem behaves just like Mentem in regard to requisites, then it would seem like heat is also not being considered a quality (I would prefer say "part" or similar, but I'm using the same word you used.) of the body, either. Imaginem also works this way. But Animal and Aquam work differently with the human body.

heat is a property of the body in the fact that the humors (choloric humor being fire) is a part of the body, and thus there is fire as a part of the body, the same way there is water (blood) running through it. However heating or cooling a body with corpus would not work. (though making it more resistant to heat or cold might)

Sure, for Elementalist magics. But for Hermetic magic? This is why you can do Corpus stuff with Elementalist Air, Elementalist Earth, Elementalist Fire, and Elementalist Water. Elementalist Fire will let you cure a coughing disease, while Ignem will not. Elementalist Fire will let you make someone angry, while Ignem will not. It's quite clear that Elementalist magic follows such humors while Hermetic magic does not. And we were talking about Hermetic magic's Ignem. Does Hermetic magic consider heat to be part of a person like their fluids (Aquam with Corpus) or just connected but more separate like a mind (Mentem, no Corpus)?

It took me a little bit to explain why I find this argument problematic. Consider the following: You have a castle on flat ground and desire a moat. If we use PeTe on sections of the ground to remove them, we will have a better moat than before. Or if we want a pit trap we could use PeTe to make a hole in otherwise flat ground, and we will have a better pit. So are you saying PeTe cannot destroy a section of ground?

The difference here is it's not about perfecting ice, but about bringing it about by destroying heat, just like a moat or pit is brought about by destroying earth.

So heating air, water, and earth is the form of Ignem is what you are saying?

If you want to give ice the unnatural property of “hot”, that’s then Ignem?

RAW ReCo can overheat a person. Anyone with Medicine knows the lungs ventilate the heat of the body to cool it.

Where in RAW does it state that you can overheat a person with ReCo?
and making ice hot would require MuAq(Ig), or MuAq (to change the property of its melting point) with CrIg(to heat it up) so yes, Ig is required.
I can't even find where you get the idea that heat is expelled from the lungs. It certainly isn't in Arts and Acadame under their descriptions of medicine...

Personal is destruction and in my interpretation closely resembles the modern concept of entropy.

Using PeTe on a moat makes the moat 'worse'. If you want the moat to decay as though eroded or have it's earthen walls collapse and fill its deepest areas, use PeTe on the moat.
Using PeTe on earth makes the earth worse, making a hole. Feel free to make that hole into a moat with ReTe or CrTe. But if you expect to make a hole that has fine or detailed complexity, you are mistaken.

When using Perdo you have to consider the Form, in an Aristotelian sense, of the thing targeted not simply it's Matter. Which gives me the thought maybe much of variously seeming inconsistencies can be fixed by adding a +1 or +2 mag Matter, similar to "part". What you describe when using Perdo to refine a moat is using Perdo to destroy, annihilate, a portion of Matter of the particular element.

PeIg should not be unique in ability to destroy heat, it should destroy that which makes heat, the element of fire. Ignem is inconsistent with the setting and too powerful otherwise. Destroying a heat source and cooling are subtlely different. For sake of gameplay and versatility I would refrain from suggesting to remove cooling from Ignem. I instead simply add spell guidelines of similar effect to other elements.

Using PeIg to disrupt Vital Heat of the body is perfectly sound. However so should using the Form of appropriate Substances , the elements, which compose the Form of Corpus. I do assert conceptually what happens is PeIg interacts with innate heat sources of Matter. Mechanically I don't think anything should change.

ReCo 15: Direct the flow of bodily energy, Arm 134. Though one could use ReCo 3 or 5: invoke a symptom of a disease, like a mild/major fever, AA 55.

You misunderstand. I didn't ask if one needed Ignem as a requirement, I asked if the Form of Ignem now governs that effect, meaning the primary Form is Ignem. Changing the melting point would melt it. I'm speaking of ice which is hot.

It's inferred in A&A. Air is brought in through the lungs to create Vital Faculty. Exhailed air is it's waste product, which includes excess heat.

According to Aristotle excessive heat generated in the heart that is unable to be expelled by the lungs can lead to a self consuming flame, spontaneous combustion. Though one may consult an Authority on the subject and double check if Hippocrates or Galen support this notion. Arm pg 66, description of medicine lists the Authorities on the subject.

I still think Ignem is not related to ice - not directly. It cannot invoke ice magically.

-Use PeIg on a tree : you don't get ice, but a cold tree (and maybe a dead one).
-Use PeIg on ground : you don't get ice, but a cold ground (permafrost?).
-Use PeIg on air : you don't get ice, but a cold atmospher (and maybe snow).
-Use PeIg on a lake : now you get ice, but it simply is cold water. The ice is a side-effect.

In a similar way, you can change your face into a face with three eyes, two noses and five mouths. This would be a MuCo spell. Chances are people will be frightened by your new appearance. But this will not mean Corpus intrinsically is related to Fear.