What should be the effect of casting two (different) Aegises on the same area? Possibly with different sets of participants?
I think I'd personally go for "consider only the stronger that applies to each individual"; do you all agree? (That's likely! 
)
It's like magical ven diagrams. The more precise protection would apply within each...Those who participated in the inner most Aegis would be unhindered throughout the covenant, those who only participated in the more outer Aegis would find themselves at a penalty within the inner Aegis...as long as it was cast by a member of the outer Aegis.
-Ben.
You're assuming there's an ordering on them. But what if
aegis 1: Cast by A, B and C
aegis 2: Cast by A, B and D
I figure C would be penalized by aegis 2, and D by aegis 1, regardless of which aegis is stronger or older or larger in area.
You're assuming the second casting (assuming it wasn't the same people) could overcome the casting disadvantages of the first Aegis.
If the same people were involved in the casting of both (or you're talking about people not involved in the casting), then the strongest (most powerful) Aegis would predominate over the area. If the two overlapped, then the most powerful would predominate in the overlapping area.
- Alex -
I'd say you are affected by the strongest Aegis active in a given area for which you don't have a casting token, regardless of which was cast when.
So an Autumn covenant (or a mystery cult) could literally have an Inner Circle. Interesting...
BTW, I agree that the strongest Aegis applies to each individual, and that one needs to remember that the penalty of the inner Aegis would apply to the outer Aegis.
I'd say so too.
OK, so you have a beef with the covenant of X. You wait for them to be busy elsewhere, then get your sodales and lay down an aegis AROUND their aegis, just a little farther out from the buildings, that totally overlaps the original aegis. Suddenly the entire covenant has a big casting penalty. Of course, this would be done in the context of a legally declared wizard's war to avoid legal complications, otherwise it would be a high crime , serf's parma, for depriving a magus of his power.
You could cast an aegis around a town or other area where you expect the have a showdown with something mystical (as long as they are elsewhere at the time) to get a tactical advantage. HEH HEH HEH
Does this scan?
Perfectly.
Yep. This was discussed a few months back (somewhere... maybe as a way to soften up a dragon???)
Since there is no "Perdo" aspect, the second Aegis would apparently(?- see below) not "erase" or cancel the first, but would co-exist, both areas overlapping and both functioning as intended, if also potentially interfering with the various spell casting and such within them, etc.
But getting that second one there in the first place is easier said than done...
Before we talk about which cancels what, it doesn't matter at all which was cast first, nor necessarily(?) which is strongest - only whether or not later ones were successful in their goal.
One of the points of an Aegis is to resist magical effects (p. 161, Aegis of the Hearth)- so the 2nd ("aggressor") spell would have to penetrate the first, neh? Otherwise, the 2nd would only be in effect in that area where it lies outside the first, a hollow bubble outside the intact sphere of the original aegis. (Venn diagrams indeed!)
(A different and legitimate interpretation could be based on the phrase "If the foreign spell cannot penetrate a resistance equal to the level of the Aegis, it fizzles out" (AotH, p 161). This would mean that the new Aegis is "all or nothing"; it either penetrates, or doesn't work at all, anywhere. However, that may be assuming a more narrowly targeted spell- under Penetration, it also speaks of a spell effecting some targets with no/low resistance (like the area outside the Aegis?) but not others (the target area within the Aegis?). ymmv.)
So, either way, unless the 2nd Aegis has a large enough Casting Total (see p 82) to penetrate the 1st Aegis's resistance, it's largely a waste of vis and effort. Against large Aegiae*, this could indeed be a challenge.
(* Or whatever the plural of "Aegis" is... stupid Greek.)
(Unless I'm missing something?)
As for whether both or just the second is in effect... several phrases could be cited from the rules, but none address the issue directly - "What happens to spells pre-existing in the area of a newly cast Aegis?" The answer... nothing. At least, nothing is mentioned in the spell description (161), and that makes the most sense imo - to risk/guarantee canceling every running spell with the the Aegis when it's cast would be completely impractical.
So, the second Aegis does not "erase" the effects of the first- there is no Perdo component, it's not intended as a "cancellation" spell against existing magical aspects, it's a protection from new arrivals.
So...
o The Second needs to penetrate the Magic Resistance of the First to exist within the area of the first. (If that fails, it most likely still exists in whatever of its area lies outside the area of the First.)
o The First continues as normal (unless a Perdo Vim is used/included to cancel it out.) In the overlapping areas all penalties exist, but do not stack.
Altho' it's counter-intuitive, a lower magnitude Aegis could successfully "penetrate" a larger one, and then both co-exist. If it's "Casting Total + Penetration - Spell Level", then the actual Level of the spell is not relevant, only the penetration total. (And in fact smaller spells have a better chance since more Casting Total can be directed at the Penetration.)
Related (and obvious) question- can an Intellego Vim spell "read" the level of an unfriendly Aegis without having to penetrate it? (That is, one that the casting mage was not a part of.) The Aegis resists Intellego's vs objects it protects, but does it protect itself? Are there any Intellego spells that can work around this sort of protection, reading the protective spell itself, not what that spell protects?)
Hm. I wasn't aware that the Aegis shielded against spells cast on the area protected, if the caster has a casting token. Does it? Does that mean you have to Penetrate your own Aegis to use Leap of Homecoming to get into it? Or to send messages by magic to your cohorts back home?
I just don't remember whether it is that way; don't have the books with me ATM. But if it's not like that, then the proposed "Inner circle" and "outer circle" could well coexist without either having to penetrate the other. Provided the casters have the necessary tokens.
Tolkens are only needed for invitees - anyone how took part in the ritual (including demons in possession of a member of the covenfolk) can ignore the aegis. The tokens are only used to invite new people into the aegis (which hopefully should prevent said demon from inviting his friends).
Sigh. No, of course not. Where did yo get such an idea???
However, regardless if whether the caster of the new Aegis is/is not a (token) member of the previous Aegis, the new one still needs to penetrate the old- the membership simply makes it an easier proposition.
The membership does not change the rules re casting/penetration, it simply makes the math more friendly; "more", but not automatic.
If you don't understand the necessity for the penetration, it's like this:
- A spell exists.
- A 2nd spell wants to interfere with it, so must penetrate it.
- IF it penetrates, great - if not, no luck.
- End of story.
Are you saying there are general rules about spells Penetrating other spells? I had no idea! Is this in the ArM5 book or an expansion?
What is the mathematics then, and how is it affected by having a Token?
Penetration Total (page 82) = Casting Total + Penetration Bonus - Spell Level
Casting Total = Technique + Form + Stamina + Aura Modifier
Muto Vim Guidelines (page 159)
Aegis of the Hearth (page 161)
This is for spells cast outside the Aegis.
Right. But none of this is general for any spell, as the proof sequence
seemed to imply.
Anyway, does the last quoted text say whether the Aegis must be penetrated even by those with tokens (or who were participants), or is it silent on that point? (No, I can't wait until I get home to check it myself 
)
I just want to know what
means. If membership doesn't render penetration entirely moot, as I thought, what does it do?
Penetration Total (page 82) = Casting Total + Penetration Bonus - Spell Level
Casting Total = Technique + Form + Stamina + Aura Modifier
What isn't general about this?
All spells must penetrate to have an effect.
Anything with a Might Score (also includes Hermetic Magi)
I was talking about spells with magic resistance, that is, spells having to Penetrate other spells, not about spells Penetrating in general.
For example, if you cast a Muto spell to transform a person (without any MR of his own) into a frog, when he's already transformed by another spell into a bat - do you have to Penetrate the existing spell? I just don't know if there is a general rule or not. Cuchulainshound seems to be saying there is.
The Muto Vim guideline you quoted is somewhat relevant, but I don't know if it constitutes precedent for all spells. Muto Vim spells are, well, strange.
If there is such a general rule, then I can understand why casting an Aegis over an existing one needs Penetration even if the caster has a Token - otherwise, I can't.
So, the quotes on the Aegis do not say anything about the effect of Tokens or participants on spellcasting from outside the Aegis. I guess you have to house-rule it. I'd rule that you bypass the Aegis - it's as if it "suppresses its Parma" for you. Otherwise, you couldn't send messages into it and the like.