How does the Aegis work

I think there is an imperfect consensus that things like Familiar bonds are not affected per se, beyond what is in the text of the aegis - might, enchantment - for the main reason that most groups apply the written rules and how they understand them, and since the word Familiar isn't in the text of the spell, stop there.

Imperfect because some groups may interpret that the Aegis has an effect by extrapolation. Shroedinger's familiar would not necessarily exist in a game, but would definitely exist on this forum until a final errata is achieved. :smile:

There are threads from time to time as to where the familiar cords are supposed to be and how that interacts with other things. For example, if a magi and familiar are facing a different door of a single circular room, each door placed at the opposite of each other, and both doors are closed. Does a magi in that circular room with the second sight virtue know they are outside because he will spot the cords going from one door to the other one? Or does he not see the cords because they can only be seen when either or both the magi and familiar are seen? What about the cords between a magi and a familiar on two sides of Europe, one of which is in a regio? Can they be observed in a well placed underground cavern midway due to the curvature of earth? I assure you sir, those cords are the embodiment of Schrodinger's cat. Because you can only if they are there or not if you look and ask your storyteller. If you don't actively ask for your second sight roll, he'll forget whether they might in fact be there, and you'll never know their quantic state.

Who the heck adds a major aspect of a spell like that at the tail end of a paragraph of unrelated other effects? Okay, apparently I have missed that for years. On the other hand I think the whole thing works much better without that effect.

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Hello there,
First ever post for me since i read Ars discussions for years. I'm french so...sorry for my bad english.
Since few weeks i followed discussion about errata, aegis clarification/modification,etc.. and it's realy annoying me.
David Charts initiative was realy good, but things realy go too far. You seems don't just makes errata, but change RAWs , and the concept of Ars Magica 5th.
Every one can (must IMO) house rule the game, but change RAW makes Arm5 not Arm5. If you want Aegis ,or Parma ,or Circle/Ring, or as you want , works in a maner or another, just do it (r) . No need to change RAW.
PS: i have ever played Aegis like Silveroak, and i don't have ever any problems with Aoth.

The Longevity Ritual creates a magical anchor, sustaining the vital life force of the magus, often by directly affecting the tissues of the magus’s body... The ritual takes a season, and culminates in some sort of focus...
...A Longevity Ritual’s effect lasts until you suffer an aging crisis (see “Aging” on page 168). After this, the ritual loses its effectiveness and the focus must be repeated...

Look at that. It's the focus that is repeated, not the entire thing. The Longevity Ritual loses its effectiveness with the aging crisis, but the Longevity Ritual hasn't cease to be. Afterward only the focus needs to be repeated, not the entire process. And then the Longevity Ritual regains its effectiveness.

Note how this breaks it into two things: laboratory process (huge thing plus quick initial focus) v. the focus ritual only (to regain the effectiveness), which matches the vis use. This is quite different than creating a Ritual spell, where the process doesn't fire off the spell at all, and the spell is just used on its own whenever.

Maybe it's wrong, but it matches the core book's description, the description of vis use in TMRE, and the description in the PeVi guideline. Meanwhile many other statements don't. Having read the core book's statement this way as well as the PeVi guideline this way is how I was doing the vis costs properly before TMRE.

Yeah. Not touching that…

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A bit more on my thinking in these four cases.

ArM5 AotH RAW dispels effects created by non-natives and brought into the Aegis. (This was made explicit in ArM5, which may be why silveroak wasn't aware of it; it's entirely possible they had never read the ArM5 description of AotH. "Wait, that's not in the current edition?" is a very common experience.) It does not disenchant items, but it does dispel their effects.

Parma is such an effect, so it gets dispelled. It has no casting total or Penetration, however, so it is easy to put it back up inside the Aegis.

Familiar and Talisman bonds are enchanted items, so they remain, but their effects are dispelled. However, the items constantly maintain the foundational parts of those effects, so they immediately come back up.

Longevity Rituals are sort-of enchantments, but they can fail and be restarted, as @callen notes. The most consistent approach would probably be to have the Longevity Ritual fail as if there had been an aging crisis, but that costs (potentially) a lot of vis, and so would have a major impact on how the game works, at least in a lot of players' heads. So that should be avoided. Fall back to suppression. However, it could also be handwaved to work like familiar and talisman bonds.

That might lead to blatant metagaming: "Wait, it is summer and my character's Aging Roll is in Winter. So she does not need her LR right now. And in she sneaks, bones creaking ..."

EDIT: That metagaming will fail with a bang, if the natives have PeCo spells based on the level 15 Guideline "Age Someone 5 years." By HP p.86 KIss of Ageing these explicitly force 5 aging rolls at once to those 35 or older, and thus may send the overconfident maga to her deserts.
So Murion will not enter any covenant but Durenmar, even on invitation: "That's an invitation for assassination, child ..."

BTW, how conspicous and noisy is putting it back up? Another issue is, whether the Aegis dispels a Parma, that the magus entering has currently suppressed by concentrating?

That's already been handled:

(RoP:F p.129) This may affect a Hermetic Longevity Ritual, though it must be suppressed for at least half the year or the target will still receive its benefits.

So a little suppression now and then doesn't really matter, and what season it happens in doesn't really matter.

I can't say for sure, but it is a 2-minute "ritual," so seems like it should be extremely obvious to anyone observing the mage and probably quite obvious to anyone in the room or similarly close.

That is specifically for suppression through a Faerie Power based on Ware. A similar rule for suppression by Aegis would be possible - but is not yet stated.

Well, it's a statement of how the LR responds to suppression. It's also pretty consistent with other situations that make statements about half a year with regard to aging. (I think there is a single exception to that general trend.) So I would doubt suppression would work differently with the LR. Of course, that doesn't mean AotH has to suppress it, perhaps ending it like a crisis does. But if AotH is going to suppress it, do we really want to start coming up with a whole bunch of different mechanics for suppression based on the source of suppression?

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LR gets errataed anyway. @David_Chart : So what we need to do is, write down there what it means to suppress it.

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(more in general, what it means to be without it, for any reason: e.g. if it "burns up" in a winter crisis, and for some reason you can't renew it until the beginning of summer).

Given that the current edition is going on 17 years old, this is...simultaneously disconcerting and encouraging; it speaks very well of the product that it has maintained its users and to a large extent its community of users for long enough that this can even be an issue.

Edit: Also, maybe, possibly, speaks poorly of us-the-community...we've had almost 17 years of recruitment to talk to friends and random people on the internet and get more people into this incredibly cool game and still so much of the community is grognards that previous-edition legacy errors are so common...c'mon, we need some new blood!


Not much time, so quick thought.

One of the things my character over in Andorra is thinking about, is how to replicate, as much as possible, an Aegis within a Structure.

How would this go?

  1. 4 ReVi wards (1 per realm) to keep supernatural beings outside. Must penetrate.
  2. 4 PeVi variation on Impede the intermitent interloper (p109 of Transforming Mythic Europe), but using the "any magical effect" guideline. This would block outside effects coming into the zone with a level under half (base + 4 mags), without any need to penetrate, and effects cast inside if this penetrates.
  3. 4 Perdo Vim effect to reduce casting totals by half (base level + 2 mags), one per realm. Needs to penetrate

And that's it.
If you wanted to add a dispelling effect, you'd need to add 4 PeVi effect, working on supernatural workings within the zone. This would need to penetrate if the spell is under MR (like, under the parma)

Main difference from the Aegis, at a glance:

  1. Much, much less effective
  2. Does not discriminate between friends and foes
  3. Requires Perdo. In fact, this is much more Perdo than Rego.

IMO, these differences showcase easily the Aegis as a great and powerful breakthrough, difficult to replicate even with centuries of hermetic progress.
I don't think it needs more advantages over "regular" hermetic magic, and I believe that having it otherwise conform to it would make things tidier and more credible.

Under these, this could mean the aegis:

  1. Needs to penetrate to keep beings with MR out, if their might is under the aegis
  2. Effects coming from the outside to the inside, under the level of the aegis, are blocked, period
  3. The aegis reduces your casting total by half its level. Needs to penetrate.
  4. This is an expansion, but not unlogical: You can't cast anything inside if its level is under half the level of the aegis. This needs to penetrate, though
  5. The aegis dispels effects crossing its borders. This needs to penetrate.

Yes, it means that if a being is powerful enough, it can mostly shrug of the Aegis.

This is a feature: Having a great Dragon, or the Queen of Summer, walk through your Aegis and do as they please is, IMO, very thematic, and a good reason not to piss them off.
OOTH, if it penetrates, it is a much more effective defence, since it suppresses supernatural effects, including skinchanger

Likewise, it emphasizes the importance of Penetration, and thus, of Day of Communion. IMO, this is a plus: I want my magi to all join their forces to cast the Aegis.

As an aside, I find it interesting that "replicating" the Aegis ended us using Perdo Vim a lot more than Rego Vim :slight_smile:

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The important feature you can’t seem to replicate with all those separate effects is that those effects can’t be ignored by those who are part of the ritual and invitations can’t be made. In many ways that’s the true major benefit of the Aegis, its selectivity.

  1. and 3. would warp those inside the Aegis, right?

Hi, I took enough time to read everything, then I decided to register and read on) Thanks for such a lot of information. :v:

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All right, I've been trying to catch up on this thread, and it's been very difficult, what with the many replies and many arguments to and fro.

I like @David_Chart's latest clarification, from August 18th

I like it that Aegis needs to Penetrate, in order to keep creatures of Might out . I've felt for a long time that the Pen of Aegis should be important. It seems silly that for most other spells, which directly affect things or people with resistance, you scramble to reach highest possible casting total. But for the mythic protective spell of the order, you can just limp through the casting, becoming fatigued (but this does not matter, because it is cast off-screen) and just barely make it.. IMHO it is more mythic, and thematically correct for magi in a covenant why by definition band together for mutual protection, must work together to cast Aegis of the Hearth using Wizard's Vigil.

I have somewhat fo a beef about magical devicesstill. It's nice that effects that need Penetration have it reduced. But it's still very easy to use the fire want to toast all the grogs and set the buildings on fire, completely unhindered by the Aegis. It is still a magical effect, but when Penetration is not an issue it doesn't matter. Id like it if: All magical devices effects which have their Penetration reduced lo less than 0 are suppressed by the Aegis.

As for tings lige Longevity Ritual, I had not considered this, since I view it as a thing very personal to a magus, inside said magus, and just somehtign that runs in the background. But it won't ruin anything for me if Aegis affects it. magi using LR who stay for longer time at a covenant had best get invited. those who don't - tough cookies.
Talismans shoudl have their effect reduced in Pen, after all it just a device. I'm unsure about Talisman Attunements, but I assume they are unaffected? The staff still gives the bonus to 'project bolt or missile ' but the cating total for such spells isalready reduced.
Familiars...the Bonds should be affected, for sake of Aegis affecting everything, but how? Familiar powers have Pen reduced, but thna again not all may have nor need Pen.

This discussion seems to be settling down. I will work on a new text version, aiming for clarification rather than change as far as possible, over the next couple of days.