Aegis vs. Parma

One thing I have seen bandied about in a couple of sagas that I've been watching is the concept that an Aegis of the Hearth either can, or does, dispel a magus's Parma Magica.

I have read the spell description and am hard-pressed to find anything in support of this position. The closest thing that I can come up with is "If the foreign spell cannot penetrate a resistance equal to the level of the Aegis, it fizzles out. The Aegis is also able to block...spells that were cast before they entered the Aegis, such as an invisibility spell cast on a magus outside the Aegis."

A Bjornaer's ability to change shape s also affected by an Aegis (per HoH: MC, p. 22), and an Aegis also supposedly impairs other Supernatural Abilities (although I don't remember ever seeing a cite for that).

Does an Aegis of the Hearth, in your estimation, dispel a Parma Magica? And, if so, does it do so always, or only under certain circumstances (i.e. there is some correlation between a magus's Parma Magica ability and the Aegis Penetration).

From a purely social POV, if Aegis dispelled PM you would distrust every magus that came to visit you. Also, (noble's parma) I don't think Second Sight is affected by the Aegis, you might consider PM the same kind of thing.

That, and you would never leave your own covenant. If you were to visit another covenant and were given a casting token, you have no guarantee that someone else involved in the casting wouldn't invoke your invitation for any or no reason. And it would make Tribunals all but impossible, for the same reason.

You have this turned around. Every visiting magus would distrust magi of the covenant they are visiting.
But yes, social issues are problematic in this scenario. However if the Heartbeast is affected why not Parma Magica?

The Heartbeast itself isn't affected - if you're in Heartbeast form and you enter a foreign Aegis, the Aegis won't force you into your Human form...but that might be as much a function of the Heartbeast's pure unadulterated awesomeness than anything else. The Aegis does affect your Heartbeast Ability, when you try to change from Human to Animal form or vice versa by making you roll your Sta + Heartbeast vs. an Ease Factor of 3 + (Aegis Magnitude รท 5) when a roll isn't normally needed.

I can almost see, by extension, requiring a Parma Magica roll when you perform the Parma ritual at sunrise/sunset vs. a similar Ease Factor, and am considering proposing a house rule to that effect for Canaries when I start it up again. But that's not the same as your Parma collapsing when you cross the boundary.

Very strange that this questions pops up after more than 3700 posts :stuck_out_tongue_winking_eye:

The way we play it, Both are breakthroughs that are not fully integrated into hermetic theory. Parma is the big thing that Bonisagus did himself and then his fili created the aegis based on that research so I think we can set a few exceptions without breaking the setting/rules

Aegis is a ritual and parma is somewhat one also so they can interact at the same level of suppression/dispelling.

So, in a couple lines

1 - Aegis needs to penetrate the parma to have full effect
2 - Parma is not suppressed/dispelled by the Aegis

Full effect is defiled as applying a casting total penalty to all magic and suppressing all spells of a level less than the aegis
Partial effect is defined as suppressing all spells that are not personal and of a level of less than the aegis

This has the effect of having both the parma & aegis add up to protect against magic within an aegis.

May not be 100% canon but it works well


Works for me!

I'm in favor of parma not dropping when crossing an Aegis boundary, but I could see sagas working either way. If it dropped it would make for a more insular, suspicious Order. Not necessarily a bad thing.

Right, thanks.

As written down in ArM5 basic rules, Aegis of the Hearth protects - in different ways - against spells and their effects, enchanted devices and beings with Might score. Nothing else is mentioned as affected by the Aegis. I do not find any reason in ArM5 basic rules why the Aegis would have any effect on Abilities like Entrancement, Enchanting Music, Second Sight - or indeed Parma Magica, which is by ArM5 p.66 "a special ritual (not a ritual spell)".

it appears indeed, that for any argument about the Aegis affecting the Heartbeast Ability at all we needed to wait for HoH:MC.

And that is a precedent for a general procedure I would - also for systematic reasons - expect to be followed in the many subsequent rules books, already published or still to come: If some new type of magic, not based on spells, enchanted devices or Might, is somewhere introduced, its interaction with the Aegis should then and there be defined, too. E. g. in HMRE p. 7 you find it followed nicely.
As typical for sets of game rules whose complexity grows with each book, this procedure was not followed through completely, though, and a structural problem in the rules came into existence. individual sagas needed explicitly or impiicitly to define their own rules on interaction of the Aegis with the many different types of magic appearing over time. Which naturally led also to discussions on interaction of Aegis and Parma - in particular if the mentioned structural problem was not even acknowledged.

Not at all. In the ArM5 rules there is TMK not a shadow of a reason for this, and TMU the game world - which is a lot older than ArM5 after all - would not be improved by any interaction of Aegis and Parma either.


I think the intention is that it would make supernatural abilities more difficult to use, it may not have been stated as such in the text of Aegis of the Hearth, but the intent is clear, to block outside magical effects. Chris Allen did an excellent analysis of Aegis here. In a game setting where supernatural abilities are used with full effect within a foregin aegis, well, I would be mighty peeved if the SG brings an NPC with Enchanting Music and sings most of the important covenfolk away like the Pied Piper. This is the kind of thing that magi have the Aegis to protect against: the primary purpose effect of the Aegis is that it protects covenfolk so magi aren't always called away to take care of a pesky problem.

Parma Magica has a magical effect, and it can be knocked down by spells like Wind of Mundane Silence, so the rules are much more ambiguous than you suggest. If one effect can knock down Parma, why not Aegis? Note the spell indicates that it doesn't have a Perdo requisite, which suggests that according to Hermetic Theory it should have a Perdo requisite.

Your or Chris Allen's reasoning is what I would expect troupes to make, once they start looking for saga house rules about the Aegis. Note that it is reasoning faute de mieux, trying to substitute for non-existing rules. It first requires an acknowledgement, that rules are missing, and then a conscious effort to make them up for your own saga. It is of limited use when addressing questions related to other sagas, like here Peregrine Bjornaer's.

I can't follow you here. So one PeVi spell (made for general dispelling) can bring down a Parma, and for you this leads to a ReVi spell (whose description does not hint at that in the least) to bring down a Parma as well and hence need a Pe requisite?

I'm inclined to take this as an example of the more funny arguments generated in many troupes, as the current rules-coverage of the Aegis with respect to the many different types of magic is lacunary.


Well, of course rules are missing, it's completely unreasonable to expect that every contingency has been thought of. So why wouldn't someone reason out what Aegis can reasonably do? I believe you are presenting a false premise, that the Aegis has holes which can be exploited by Supernatural abilities. I don't believe that's the case. Yes, it takes some reasoning to arrive at that conclusion. Yes, people might disagree with it, but I think it's entirely reasonable to trust that the authors intended Aegis of the Hearth to be effective against all forms of magic, realms, abilities, and Arts.

Lacunary? Not really. The very first statement, "This ritual protects a covenant in the way a Parma Magica protects a magus" pretty much sums up that it should not be read as having holes. Parma Magica is effective against magic from all realms AND it is effective against supernatural abilities and powers.

Take a mundane with a spell cast on him by a magus foreign to an Aegis. The mundane walks across the Aegis boundary, might the spell get dispelled, or be blocked by the Aegis? Without a doubt, yes. It is explicitly stated in the text. The mechanics for adjudicating how that gets blocked aren't stated explicitly, but I would compare the CT of the spell to the Aegis to determine whether it can penetrate the Aegis, treating it as if the spell were cast at a target within the Aegis. That behavior is most like a Perdo Vim effect and indeed, there aren't any Rego Vim guidelines present which have such an effect.

Take a magus with a spell cast on him by a magus foreign to an Aegis. He walks across the Aegis boundary? What determines whether the spell gets dispelled? Overcoming the Aegis with the CT of the spell -OR- the Aegis overcoming the Parma Magica. A spell cast at personal range is effectively within the Parma Magica of a magus. How does this get resolved? If the Parma Magica can be overcome by the Aegis, then the spell is dispelled. If the Parma Magica can be overcome by the Aegis shouldn't it be 'dispelled' as well?

I suggest you actually read the analysis Jonathan referenced. Or, if you did, I suggest you reread it more carefully because it seems you drastically misread it.


I guess that I understand you here. And you see that you are making a very weak argument, right?
In particular since there are kinds of magic, realms and abilities that a covenant might not need or even wish any protection against, like e. g. Second Sight, Sense Holiness and Unholiness or such. So not protecting against such magic - as with current state of Aegis rules - might appear to be as reasonable to certain troupes.

Then show me were the interaction of Muspelli magic and the Aegis is defined. (And yes, I agree that the Aegis needs to protect against most or all of that. :slight_smile:)

That is a very weak argument again, based on a sweeping rhetoric analogy. Were that analogy a true technical statement, the definition of the Aegis would have to be completely different.

Why would it? By the rules we have it is clearly not. And by looking at the effects such 'dispelling' would have on the game world, we see that it was certainly not planned for - and then omitted by mistake - either.


Hi Chris,

you did good work on that contribution, Congrats.

in particular by marking the relative truth of your statements. With your reasoning, you laid quite some groundwork for troupe decisionmaking.
You don't replace it, though - and it was not my intention to qualify your work specifically as house rules.


Except that this isn't a hypothetical (well, except for the fact that any discussion of Ars Magica magic is almost by definition hypothetical :smiley: ). This actually came up in a saga that I was in, here on the boards, and was discussed as a house rule in another (although with an actual mechanic instead of shredding by fiat). It's also relevant in that I'm running a saga and would like to know what the rules provide before I decide whether to house-rule it one way or the other.

It seems to me that Aegis of the Hearth could just as easily be Pe(Re)Vi, in that some of the effects are clearly Rego (blocking or repelling those with Might), while most are Perdo (blocking Intellego spells, blocking or preventing effects installed in Items from working, dispelling magic cast on a person outside the Aegis who enters the area of effect).

To be honest, I'm pretty sure I know what the answer would be for me, but I'm still new enough at running things that I'd like to be sure I'm on solid ground rules-wise, and the fact that the one story guide was adamant that it was raw gave me a sliver of a doubt.

Oh, and I'm in agreement that callen did a whale of a job on his Guide to the Aegis of the Hearth. I have it bookmarked and reference it on occasion. But this is something that (I'm guessing) never came up before, and may warrant a line in there someday if we ever reach an accord on this.


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Thanks :smiley:
It's always good to have a clear and official answer :smiley:

Well, it seems to me things are not that clear.

For exemple. Aegis protects like Parma.
And Parma doesn't dispel magic.
If you're invisible and try to strike someone protected by parma, you don't become visible, you're just blocked.

The beginning of the Aegis description stays with that "blocked" spirit. Trying to teleport inside the Aegis doesn't work, just like trying to teleport "inside" a parma wouldn't work. Cast a spell towards someone inside the aegis, and the spell is blocked, just like if he was inside a Parma. Similarly, if you try to use an Intellego spell on a target protected by parma, the spell is blocked. Everything's fine.

Where things may be confusing is when we get to other spells: The Aegis is also able to block foreign Intellego spells (...) and spells that were cast before they entered the Aegis, such as an invisibility spell cast on a magus outside the Aegis.
What does "blocked" means here? Some people take it so that the invisibility spell is dispelled, which is quite another word. Some, myself included, take it so that, just as with the above exemple with Parma, you can't enter the Aegis while invisible, just like you'd be blocked outside someone's parma.

Note, though, that Rego Vim also has a guideline for supressing spells. So, by analogy, I can see some troupes ruling that the above invisibility spells is supressed while you enter the Aegis, only to come back online when you exit it.
I must say that, even if going with the "dispelling" rather than the "blocking", I prefer this a lot, since it means you can't use the Aegis to destroy curses laid on you.

Oh, also, for the record, How does Aegis interfere with skinchanger? :wink:

The closest argument by books that I know is in TMRE p.7: Hedge Wizard powers are affected by the Aegis, hence a Folk Witch's Shapeshifter power is. And carrying that over to Skinchanger is not really a strain. :slight_smile:


callen's magnificent opus actually addresses this, if not by name.

Since there's no Ability or Art associated with Skinchanger, I'd say that it's unaffected by the Aegis.