Would a magically created bright flash of light be resisted by Parma?
That's one of those tricky ones. So, I'm open to guidance or coming to an understanding.
I think if you create something that can blind people temporarily, the species are "natural" and therefore bypass resistance. However, this has implications for everyone, and it could make things bad for both sides.
From reading on PM and basic principals I would say yes it could simply because having a magical light would be unusable by magi if not. There is a spell at is CrIg15 Flash of the scarlet flames (ArM140)that would do it. Jacques would have to get an high roll to pull it off so he will not try.
Now lets get tricky. I can pull the same effect via CrIm(Ig)4. Jacques might be able to pull that one off.
CrIm(Ig), so your thinking Base 1 R:+2 Voice, D:Mom, T:Ind +1 for the requisite...
Is a very bright light complex? I don't think so, but I sure don't like something that can blind as easily as that. Cuts both ways, you know. Still only 5th level if I impose some "complexity" on it. I feel like I'm missing something here.
My first reaction was that since species are natural and thus not magical in nature, that it wouldn't. But then I realized that we're talking about actual light, which is under "Ignem" and not "Imaginem", that changed my mind. I'm thinking that Ignem light is unnatural, and thus is resisted by Parma. Just my tuppence.
My vote:
CrIg or CrIm would both magically create sources of light. The light itself would be natural.
Consider:
Ring of Candlelight, CrIg 5, Touch, Ring, Circle (Base 2) creates a ring of candlelight by which magi can see. The light is not subject to Parma, or else the spell would be useless.
Wizard’s Sidestep ReIm 10 Per, Sun, Ind creates a second image of yourself. This fools people with magic resistance equally well with people who do not.
Phantasm of the Talking Head, CrIm 10, Base 2, Voice, Diam, complexity -- Creates the image and sound of a talking head. The effect is not resisted.
However, a CrIm(Ig) spell that's Base 2 for the CrIm part.....that raises the interesting question of just how much bang for the +1 magnitude buck the requisite gives you. It seems counter intuitive to me that a single magnitude would add an entire base 5 effect. Generally, what I've seen suggests that the requisite added is of lower power than the base effect. On the other hand, it does seem logical to me that a spell with requisites can achieve at a lower level something comparable to a higher level, single-form spell.
Read the spell's description, to be sure, as you may be wrong (serf's parma). If it isn't resisted, it will be written, but I believe it is.
Here's why, as far as I understand it
Light is not Imaginem, it's Ignem. The more light there is, the more bright the item. Think of a picture (the species): it is always the same, whether illuminated or not. If not illuminated, it would appear dark, whatever its real appearance (species). If illuminated enough to be painful to the eye, it'd be the same. This follows a similar reasonning.
Thus, magical light (the thing that determines brightness and blindness) is resisted.
Species (imaginem) do NOT determine brightness, that much I am sure of. It's somewhere, maybe in the Jerbiton chapter, maybe in A&A.
A very bright illusion would need an ignem requisite, for exemple.
Yup, this is how I understand it.
Yes, this is quite tricky.
As far as I can make my head around this, the important part is to forget the modern conceptions about light and how it reflects on items. To us, light, brightness, images and illusions are one and the same, while in Ars, these are separate things
Thus:
- The ring illuminates items, which are thus visible. The magus resist it just like it would resist any CrIg spell, which means... That the light of the ring doesn't affect the magus, who thus appears darker than his surroundings. If it's the only light available, he appears as a shadow. He can see the ring, but it is not luminous. Heh, this feels like Naruto
- This moves the magus species, which are natural, and thus isn't resisted.
- This creates a species emitor, which, when affected by light, emits natural species, not resisted. In a dark room, it wouldn't be visible.
Note that there's a spell somewhere (Image from the Wizard Torn, I believe) which is explicitely said to go the same way: You send your image (emited species) afar, and it is affected by the light where you are, not where it is, so if you're in bright light, it would appear bright and illuminated in a cave, and if you're in darkness, it would appear dark in sunlight.
By your logic, spells like Moonbeam, Lamp without Flame and Palm of Flame are useless to a wizard using PM because he can not see the light created. If the spell is creating the species then it is unresisted by PM
It's pretty clear that the species created are natural.
From page 86 of the MRB, the last four bullet points relate to our discussion.
• The maga can see an illusion, as the species emitted are natural rather than magical. She gets no indication that it an illusion.
• The maga can see a magically created object, as the object generates normal species.
• The maga sees something affected by a Rego Imaginem spell in the location intended by the spell, as the species are no longer under magical influence when they reach her.
• An illusion cast on the maga fails.
My main concern is being able to create a blinding light very easily, which it appears possible to do under CrIm guidelines. I'm inclined to increase the difficulty because creating blinding light is "complex" and I feel it should at least be closer in magnitude to the CrIg spell that is inspiring it. I'd like it to be at least 10th level. I may have to HR that blinding light is "complex" and "intricate" to create. I don't think that any of us want someone to be able to effortlessly create blinding light.
By adding +2 complexity would take it to 10. I would disagree that more than +1 is necessary. it is just a different way of doing something with the same system. That it is cheaper is only because the image effects only one sense where as the Ignem spell creates heat and light. It creates the element and Imaginem creates the species.
I made a pacifist Criamon at one point and he used Imaginem as his main form. If you are imaginative 
you can imitate the effects of some of the other spells much cheaper. Stench of 20 corpses is CrAu20 but the same effect can be had with CrIm 5. Same with Jupiter's resounding blow. But because of the same principle. Effecting a single sense is cheap.
I'm not trying to be a pain but Jacques needs to be creative if he is going to do anything other than hide or die.
I think I've made it pretty clear in the other thread that only one person is marked for death. Sometimes, when an immovable object and an unstoppable force are coming together the best thing to do is to get out of the way.
So a CrIm of 5 can create blinding light is what's currently on the table. I think it's within the guidelines, my concern, by making it so easy now is that it is also easy for me to use in the future, too, and so I'm cautious about saying yes, despite the fact that I think it is within the guidelines. Future teams like this with flashbangs for breech and rapid entry situations. 
Not useless.
The spell light things up, thus they are visible.
It just can't be used against someone with MR. And yes, if you try to affect a magi with Palm of Fire, he'll resist it just like he'd resist a higher-intensity Pilum of Flame. By your ruling, if a magus was covered in oil, you could inflame him with a Palm of Fire, but not by any higher-level Ignem spell
Create Light is Creo Ignem, not Creo Imaginem, and it is NOT species. The light created is magical, thus it is resisted. It's just as simple.
Where does the imaginem guidelines talk about light? Nowhere, for good reason. Contrary to the Ignem guidelines.
There's one Imaginem spell that creates light. It's Phantasmal Fire. And it includes a "+1 for light from Ignem requisite" magnitude.
Imaginem allows you to create the equivalent of a picture, or to recolor something, or even to supress any and all color, making it transparent.
Ignem allows you to light that picture, or make it shed light. Without light, your picture would not be visible in the dark. Think about it like this: Imaginem is a painter (for visual illusions, anyway), and no paint has ever blinded anyone.
You can do whatever you want, but I'd be VERY wary of allowing Imaginem to also affect light. This'd lessen again the power of Ignem, which is not the most versatile form, only to increase Imaginem's, who doesn't need that.
Moreso, if considering that species = light (which isn't the case), you're opening a whole can of worms, such as these non-resisted blinding spells.
Please, show me where do the Imaginem guidelines talk about creating light.
And explain to me why does phantasmal fire have a +1 ignem requisite to be able to create light. And why no imaginem spell creates light, while all the light creating spells and guidelines are in Ignem
Oh, and why do magi bother with a lvl 15 resistable Creo Flash of the scarlet flame when a lvl 05 Creo Im is not resisted. It makes absolutely no sense.
No.
Go read the spell again.
Flash of the scarlet flames ONLY creates light.
So, it's officiel, Ignem is Fire and magical, resisted light (normal) and Imaginem is species and non-magical, non-resisted light... This is... not only not raw, but, IMO, a useless weakening of Ignem to add a better version of it to the already-powerful imaginem.
I am sorry, but, IMO, this is a mistake, and this also opens the road to Imaginem to create poisonous air, for exemple.
EDIT: difficult to say, but I am currently quite angry due to RL events. I tried to avoid showing that in my posts, but it may and I keep re-editing them to try to be more civil, without being sure that I am, so if I ain't, please accept my apologies
It is not easy to use as you might think. Reading the Flare spell, one would have to target the face of the opponent to blind them.
Going with your ruling a flash bang, with Imaginem, would be CrIm(Ig, Au) base 2 + 2 voice +1 Ig, +1 Au + 2 complexity or CrIm20. I add +2 to the complexity as +1 for the flash effect and +1 for the bang effect. Not a bad little spell if you can pull it off but still effects 1 person. I would think the followers of Vilano would know of such things.
Reading the spell I was talking about has Ig which causes another +1. I dis agree that the flash Scarlet, when cast in someone's face, is resistible with PM. PM does not block the species that is the light.
since Imaginem can not effect the lungs it can not create "poison air" any more than a CrIm spell that looks like PoF would cause damage. Your senses might tell you it is hot but it does not burn. You might be fooled into thinking their is poison gas but it does not harm you.
No. Because magically created heat is resistible by PM. The light that is thrown off is not resisted because it is still natural.
My interpretation so far.. I'm thinking that CrIm, even with an Ig requisite can't create an image that emits light. I think it can only use the existing light, it's creating an image. If you wanted an image that emits light, I think it's CrIg(Im)... still bound by the higher base of creating light.
CrIg creates light, and it can't be resisted because, page 86 of the MRB: "The maga can see a magically created object, as the object generates normal species." The CrIg light comes from an "object" that makes a lot of light, the light is "natural" for the duration of the spell. I'm not really happy with this, but the alternative is that some magi can't see a PoF cast, because the light can't penetrate their Parma, or other weirdness. (And feel free to debate this, but I think the alternative is more complicated, and I'm not inclined to deal with complicated rules manipulations). Differing rules for spells that create light benignly and offensively, and then requiring me to adjudicate every action, is adding complexity I don't care for.
So looking at Flash of the Scarlet flames suggests targeting, but doesn't include finesse. I think a finesse roll for that is necessary since you're kind of aming it. In fact, i'd go so far as to suggest that anything that says aiming or targeting, if it doesn't include finesse in the description requires finesse.
The Fixer, I didn't get that you were angry, so don't be concerned. Just be aware that I'm trying to come up something that isn't complex and doesn't require me to make a lot of judgment calls about something in the future.
My position so far is that CrIg is responsible for creating light. CrIm cannot create light, and if you want images that are lit up, you need to go CrIg(Im) or something. Now, where it gets sticky is the magically created light. I have trouble with the fact that CrIg light can be resisted, because if that were the case, no one with high MR would ever see a PoF hit its target, or even fly through the air. Or that if someone does see it, it's because we have to rule that the effect is cosmetic and therefore not resisted. I don't like that. I like something relatively simple. If a magus can see a mgically created object, as per RAW on page 86, then it is not resisted. If that same object is emitting blinding light, well, again, I think it is not resisted.
I'm fine with it but it gos against Phantasmal Fire spell.
I'm fine with finesse rolls for targeting spells.
Yes and no.
CrIm(Ig) is creating a light of such low magnitude that it isn't blinding, at least isn't anymore blinding than a campfire[1]. It's adding a requisite for light. It emits enough light that it looks like a campfire. The Ignem requisite covers the light. If you wanted a brighter light, such as direct sunlight coming from the fire, I'd say you'd have to go to CrIg(Im). Creat blinding light from something that looks like a camprfire. The light is necessary for the effect. The light is real. Imaginem cannot create a light so bright as to blind, and the spell design for CrIm doesn't have a guideline for light, so we have to go to Ignem, and use Imaginem for a requisite to make the image.
[1]Yeah, if you're staring into the fire long enough, your eyes acclimate to the increased light level, and you'll be less likely to see stuff.