Hello there, this seems like a simple question but I just want to be absolutely certain. To turn water into ice is Rego Aquam,
So what is it to create ice from scratch? Is it creo aquam, or creo aquam with a rego requisite?
I am thinking it should be Creo Aquam on its own, because ice is a subcategory of water, because for instance creo terram can be used to create any sub-category of rock. You don't create generic rock, and then use rego (or actually muto in this case) to then decide you would rather it was marble.
I disagree. Magic still follows the physics of the world to a large degree.
Put a bucket of water outside on a cold sub-zero day and it eventually freezes. Magically create cold - normal cold - and the same thing happens.
But create extreme magical cold and the water may freeze instantly.
This is IMHO similar to creating a magical campfire- Eventually this heat will melt lead, if left over the fire long enough, the lead does not instantly melt...Unless you use a higher guideline.
Perdo magic does plenty of things in an instant (i.e., at Momentary duration) that ought to take more time.
Decay of Fur and Hide immediately destroys animal product. This is a process that would normally take years, but it happens in an instant. Comfort of the Drenched Traveller makes water disappear in an instant. It doesn't slowly evaporate; it disappears. Curse of the Desert immediately removes most of the fluid from a person's body. Again, it doesn't slowly evaporate; it just disappears. Bane of the Decrepit Body accelerates to process of aging such that you age 5 years in a moment. Physics says this should take 5 years to occur, but the spell does it in a moment. Curse of the Rotted Wood causes wood to rot in an instant. Again, this is a process that would normally take weeks or months. But it happens in an instant. Plant's Withering Bane can wither a tree in an instant. That's months of activity squeezed into an instant. Rusted Decay of Ten-Score Years causes metal to become rusted in an instant. Once more, a process that should take years (ten score years, perhaps) happens in an instant.
Why, with all these effects, would a PeIg spell not be able to create ice in an instant by taking away the heat from the water?
No, don't get me wrong - casting a PeIg Base 5 (Strongly chill an object e.g. freeze water) instantly freezes water. I just looked it up.
I just thought about lowering the temperature in a room, because then I don't think the water freezes instantly. Like "Conjuration of the Indubitable Cold" which chills the air of an area (T:Part) . But this magic is not directly freezing the water. Using the PeIg guideline above directly on the water. My bad.
In the same way CrIg Base 5 can create a fire, which if left burning long enough can melt lead. But a Base 10 cast on the lead melts it instantly.
I do agree that if the water is ancillary, like water that happens to be in a room that's chilled, it would have to freeze like normal water. I was just thinking of water being the actual target of the spell.
Well, that makes all the difference. I had not read that into the first postings, but there you have it. It makes sense metaphysically and is supported by the actual magic guidelines...sort of.
Thankfully, real physics don't work in ME, or one could use CrTe to create all sorts of PeIg and CrIg effects. Hmm. Or all sorts of other ways to create, destroy or manipulate matter to cause exothermic or endothermic reactions.
At any rate, my understanding is that CrAq will create ice, which will melt very quickly, much quicker than an normal ice on a warm day, because the ice is warm. How much quicker? Up to you, since real life science isn't an issue, only the very obvious idea that warm ice ought to melt faster than cold ice.
Want to keep that water solid? MuAq will do the trick for as long as it is maintained, maybe ReAq. The ice is a magical medium. PeAq should not work; removing the "melts" property makes the ice better in a fundamental way (more likely to remain ice), which Perdo cannot do.
Want to chill that warm ice? A Momentary PeIg.
Ice is not the most useful material even at low temperatures; an icicle is sharp but easily broken. Muto can help with this, of course.
I've always thought that since medieval people only know ice as cold then ice created with CrAq (or water frozen into ice using Rego) is cold. It starts to melt immediately, but in a normal rate according to ambient temperature.
So if you magically create a shedload of ice then the surrounding air and things in this area start to cool off.
I tend to agree with that. One of the defining characteristics of ice is that it's cold. If it's not cold, then it's just some kind of funny rock that melts.
I too agree with this for CrAq. Creo should create materials in their normal expected state, which means cold for ice.
Making ice with Rego is another matter, since one shouldn't be able to change a substance's temperature without using Ignem (PeIg for chilling, to be precise). IMO, the guideline for making ice with ReAq is a mistake.
