Automatic counterspelling talisman

I don't.

I only politely agreed to VimWabbit's admittedly pretty unclear "Shriek of impending shafts, linked with a 'Set that shit on fire if it approaches fast'. Great effect, so an old flambeau. Works." He's new, after all.

Cheers

You can do this in your game as you like, of course.

You appear to read "In other circumstances, the maga must work the Form out" as "In all other circumstances, the maga can work the Form out". I would disagree, and read it as "In other circumstances than clearly hearing and seeing Hermetic words and gestures, the maga must work the Form out". Your interpretation also contradicts directly

Furthermore it makes little sense to me, that without knowing and casting InVi spells a magus could "by sensing powerful magics" just determine a Form. For this you would need to add magnitudes to an InVi spell by:

Cheers

There's no contradiction. Non-Hermetic magic, being unfamiliar to the Magus, is even harder to understand than Hermetic magic. I believe there's more to magical combat than recognizing words and gestures.

For the same reason that Magi get Form resistance, they have a certain understanding of the magic of the Forms.

Yes, of course the InVi must be of sufficient level to give information on Technique and Form to be useful in this instance.

Exotic Casting, as you can see above, means "non-Hermetic methods to cast Hermetic spells", which "are not the same words and gestures taught as part of Magic Theory within the Order". It does not imply "Non-Hermetic magic".

Cheers

Quite true. I responded too quickly to that one. Nonetheless, I've always worked under the assumption that Magi can use fast-cast defenses against non-Hermetic spells. Is this something others do differently?

They can, but instead must succeed a Int + Realm Lore (or other adequate skill except MT) to have an idea of the power used, thus what they can do to counter it. Of course, if it is a power which does not require gesture or words or any obvious signs, the difficulty increases or could make it even downright impossible (ST call).

Core ArM5 did not yet cover Non-Hermetic magic: so fast casting to defend against it can't be expected in the book.

To enable it, I would require in general both an Int + appropriate Lore roll (Realm Lore => pretty high total needed, or Non-Hermetic Magic Theory equivalent => more average total needed) and a Per + Awareness roll.

But I certainly accept no arguments about "I am Gifted, hence feel the magic power no matter where it comes from". For this there is HoH:S p.128f Comprehend Magic: two rounds of scrutinizing a power with it should allow to ever after skip the first roll and proceed with standard Fast Cast defense against it, because

Cheers

Is this actually a published rule or is it your ruling on a topic that is vague in the books? If it's a rule, I'm not familiar with it.

My approach has always been to assign the most appropriate Form to the non-Hermetic effect and let the Magus attempt to identify the incoming spell. Even if one disagrees with my presumption that Magi have an intuitive sense of magics, the InVi spell would allow this. This wouldn't work with exotic magics that don't match Hermetic Forms, of course.

Fundamentally, I've always assumed that determining appropriate fast-cast defenses had more to do with understanding magic than with recognizing hand gestures. I suppose the printed basis for this belief is weak, but I'd say the alternative is also weakly supported. The entire set of rules for magical combat and it's details and sequencing could use work.

Its actually explicitly stated in the rules

Edit:

Exotic casting from HoH:S also supports this, it basically says that because the caster is using ritual actions that don't match with Hermetic magic theory and so it is harder to determine the form they are using

Eh. Sort of. Core ArM5 did not cover yet non-Hermetic magic in any substantial detail. I'm not worried about the bunch of little references, either. Core ArM5 explicitly addresses some dispelling of non-Hermetic magic, which is quite relevant to this particular topic.

As the assumption is incorrect, the logic doesn't follow.

I would agree with One Shot and Imreai on identifying non-Hermetic effects. I'll add Sight of the Sigil (HoH:TL p.75) to what they said. Why do we need such high level spells as this and Sight of the Active Magics to identify Technique and Form if we can already identify those without such spells? Meanwhile, it lets you see similar details for non-Hermetic stuff, and yet even with this special vision a magus "without knowledge of that sort of magic may not be able to interpret it," so it takes more specific understanding that just a familiarity with magic to identify what is being done.

Those spells let one identify the effects reliably and in some level of detail. They're useful in the same way for Hermetic effects.

I'm in the camp that believe the Form-based structure of the Magic Realm indicates that all -- or at least most -- magic matches Hermetic Forms. A Finnish Wind Wizard is casting Aurum spells and this is recognizable, even if they method he is using is completely non-Hermetic. This colors my viewpoint I suppose.

Yes but the rules then go on to say:

So if the maga can't hear or see the words or gestures, she can still work out the Form. How?

I can see why you'd read it like that. That section starts out by saying

That means that you can automatically tell what the other person is casting if they are a Hermetic Magus, to me the 'other circumstances' deal with things like non hermetic casters you are trying to fast cast a defence against or other such events.

Let me turn that around and ask what situation could the scenario you are outlining apply? If the mage cannot see or hear someone casting a spell how do they even know they need to fast cast a defensive spell? From what I remember its pretty well established that you can't tell if magic is active without using an InVi spell, and that can only detect active magic, not magic that hasn't yet been cast?

I understand where you are coming from because the rules do not explicitly forbid you, but I can't see any reason you should be able to know what someone is going to do if there is no sign they are doing it.

It could be in response to a Hermetic caster who's using the No Words and No Gestures options, outlined in the table immediately above the rules on fast casting. Or it could just be dark and noisy.

I see it as the target magus feeling magical forces gathering around him, with just enough time available to cast a counterspell. That feels like what wizards of fiction do and I've always felt Ars Magica was designed to allow us all to play those characters.

I think it makes for a more interesting game if magi can duel with spells and counterspells, particularly since Parma Magica seems underpowered in the current environment, which is so rich in virtues to boost casting totals and penetration.

If you wish to nitpick, you need to do it correctly and especially distinguish between mentioning, acknowledging and covering (that is treating or expounding) a topic.

Cheers

This means, that in your sagas every magus automatically has a very powerful version of the ArM5 p.45 Minor Supernatural Virtue Magic Sensitivity.

You know that argument to be extremely weak: "wizards of fiction" are a vastly diverse lot. In every fantasy cycle your "wizards of fiction" have different limitations, because without such limitations there is no story and no novel: this holds expecially for the basic functioning of magic and the detection and manipulation of the magic of others.

For every RPG you must come up with a single set of such limitiations to just keep game and world together. Ars Magica does that admirably, and makes its detailed magic rules a main driver of its sagas. That said, you can write all the rules for your own game.

Cheers

You mean like
9 : to have sufficient scope to include or take into account an examination covering a full year's work
10 : to deal with : treat
from exactly what you linked? You'll notice "treat" is similar. You'll also notice expound, which is about being thorough, is not stated anywhere on that page. Yes, ArM5 includes/takes into account/deals with dispelling non-Hermetic magic. And I did say "not... substantial detail" and "some dispelling." If you wish to nitpick, you need to do it correctly.

The point is that someone reading the book might well see that there is some discussion of dispelling non-Hermetic magic. After all, there is. That someone should not make conclusions that dispelling non-Hermetic magic was not considered by the authors since it clearly was considered. That doesn't tell us anything in particular about the particular difficulty level being discussed, though; it just says less than you claimed. As I said, the logic doesn't follow; but that doesn't mean the conclusion is incorrect.

Regarding fast casting, would you allow a player who fails to identify the incoming magic (whether because it's non hermetic, or they fail the identification roll) to declare that they're going to fast cast a specific form and technique anyway, on the off chance it's a valid defense?

For example, Agnes ex Bjornaer is facing off against Robert of Flambeau in a wizard's war. Robert casts a spell using subtle words and gestures against Agnes, and Agnes decides to fast cast against it. She succeeds at the speed roll, but fails to identify his spell. Knowing the Robert is a master of Creo Ignem, Agnes decides to fast cast a Rego Ignem defense, and creates a level 20 effect. The GM knows that Robert was casting Pilum of Fire, and so Agnes's defense should work against it.

Would you allow Agnes's fast cast to work, or must she succeed at the identification roll? To be clear, if Robert had cast a Perdo Ignem effect, her defense would definitely do nothing, as it's not a valid counter to Wizard's Icy Grip.

So what's your interpretation of:

It's clearly not referring to recognizing words and gestures, since that's covered by the paragraph immediately preceding it. It seems to me that you're just ignoring this rule.