Aegis vs. Parma

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.


1 Like

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.

This is how the prior item now reads:

Since it is stated in HoH:MC that Heartbeast is affected during the transformation because it is a supernatural effect at that moment, it is likely that other Supernatural Abilities used within a resisting Aegis will be similarly penalized. Additionally, HMRE specifies that hedge magician powers "cast" at or within an Aegis must overcome the Aegis similarly how spells noted above must. Many hedge magician effects come from Supernatural Abilities and are not spells, so this general statement likely applies to those Supernatural Abilities as well. [size=85]Note that Parma Magica is not countered by Aegis of the Hearth. This does not imply any Supernatural Abilities are not affected because Parma Magica is not a Supernatural Ability, plus it seems likely Aegis of the Hearth and Parma Magica were designed to be compatible.[/size]

As for Skinchanger, I would look at the item rules. Skinchanger allows you to make an item which can change only yourself into an animal.


Since Heartbeast and Folk Witch's Shapeshifter are affected by the Aegis, it would appear weird to me to have simple old Skinchanger 'slip under the radar'.
Indeed, the skin of the Skinchanger to me looks very much like the Folk Witch's fetish obtained from Skin Nitting (TMRE p. 38 and p.40), used with a CT of Stm + Shapeshifter + Aura.

Note, that a typical Aegis (say level 20 or above) by TMRE p. 7 prevents a typical uninvited Folk Witch Shapeshifter (say Stm <= 3, Shapeshifter <= 5) from entering in changed form, and from changing form within.
So the simplest house rule is, to make Skinchanger weaker than Shapeshifter (which after all requires an investment of experience points to the Ability) and have any Aegis keep any uninvited Skinchanger from entering in changed form and changing form within, too - without assigning the Skinchanger a CT at all. But it's clearly still a house rule.


THose 2 are abilities. Skinchanger is not. Skinchanger is more akin a magic item that transforms you into an animal. Since there is no roll and it does not imply penetration*, it is not affected by the Aegis. it is not that it slips under the radar. it is that it is another kind of stuff.


*Skinchanger affects you regardless of your MR. So a skinchanger magus with parma 8 and a peasant are both affected by their own skinchanger ability. You could say that it is a personal range effect (the character is the magic item) and that the animal pelt or similar is just the trigger.

Note that we are talking about house rules here anyway.

When ArM5 basic rules stood alone, there was no reason at all to have Aegis and Skinchanger interact.
At that time we recommended to new players the "Flambeau Spitfire": get an eagle or raven shape via Skinchanger for one Virtue point, Deft Ignem for another, lots of Ignem and magical combat for the rest, and then fly in and 'let fly'. it was cheesy already then, but it was legal. (OK, "Spitfires" walked around butt-naked a lot during adventures, and that gave the rest of the troupe a lot of "role playing opportunities".:slight_smile:)

With HoH:MC out some time later, the "Spitfire" turned from cheesy to fishy (and was no longer recommended), as the commitments and downsides of the Bjornaer became apparent. I recall a lot of resentment then about the new perspective of House Bjornaer wrt Hermetic shape changing. And also Bjornaer Heartbeast skill was no longer all benefit compared to the one Virtue point Skinchanger: some Heartbeast skill was indeed needed to change under a foreign Aegis. But still the Aegis and the Skinchanger had no reason yet to interact.

With HMRE out some time later again, that changed. The question arose, how a Skinchanger prepared his new magical animal skin, if his old one got destroyed. We knew that it took "a season, although the method varies depending on what the item is." Well, that is quite what we knew about the Folk Witch's Skin Nitting (HMRE p. 40), too: "If she has the Shapeshifter Ability, the folk with may enchant an animal skin in her kitchen. ... enchanting the fetish takes a season and consumes 1 pawn of Animal vis." Also, the procedure with which a Skinchanger prepares his skin is accessible even to illiterate grogs and does need time, but neither lab nor vis. All this fits with Skinchanger being a 'low tech' version of Folk Witch Shapeshifter, even doing away with the Shapeshifter ability - which helped to bring Skinchanger in line again with the rest of the shapeshifting, as that had developed over some four years after the ArM5 basic rules were published.

And as already the Folk Witch's Shapeshifting is by HMRE p. 7 very much hampered by the Aegis, the Skinchanger is affected by it even more severely. ...

Note again, that we are talking about house rules here. House rules need to respect already established character rights and histories. If a campaign contains a "Spitfire" or such, which already has decided Wizard's Wars or Marches with its ability to sneak in animal form under the Aegis and kill the target/nemesis/villain, you can't take that away by introducing above house rule.

But with over two dozen ArM5 books at hand now, I don't believe that Skinchanger can just remain the simple no interaction required, no strings attached, no explanation given power that it was when the ArM5 basic book came out 2004.


What has changed exactly with HMRE? Skinchanger does require a roll now? Didn't notice it if that is the case. Skinchanger and shapeshifter are still 2 different virtues. Shapeshifter allowes flexibility but requiresz a roll. Skinchaner does not require a roll (acts more like a magic item) and is not hampered or profits from auras at all. Where is the problem?


I think I should point out that I believe it is vitally important that most supernatural Virtues and Flaws without associated Abilities or Arts not be affected by Aegis of the Hearth. I expect we would all find it problematic if a character were to walk into an Aegis of the Hearth and all-of-a-sudden lose something quite inherent to a character like Strong Faerie Blood, Unaging, etc. Meanwhile I suspect we all don't want a character to avoid a Flaw like Ages Quickly, Greater Malediction, or Lycanthrope by living inside an Aegis of the Hearth and never taking part in the ceremony. So I wouldn't go about making a ruling that they supernatural Virtues and Flaws in general should be affected.

Just treat Skinchanger as an item effect and deal with it that way. The description for Skinchanger certainly makes sense with it being treated that way. That allows for the above without having to start house-ruling much of anything, though of course you do have to make a house rule/decision on exactly how items are resisted.