Wizard's Communion and Penetration

The more I read this forum, the more I think my understanding of Ars Magica is far less than I would have hoped. I have been particularly struggling with the A Guide to Aegis of the Hearth topic relating to Aegis of the Hearth being dependent on Penetration.

Rather than hopping in and immediately shooting off potentially disastrous opinions on the above issue, I decided to do some research first to try and see what was going on with my understanding. Now I am even more confused. I have found numerous references in the topics of this forum to Wizards Communion affecting the Penetration of spells, the usual example given is for Aegis of the Hearth, to increase its Penetration. Before I go off on Aegis of the Hearth and Penetration, I decided to begin my questions about this issue first. (Might as well say stupid things here first.)

ArM5 p.82:

Penetration Total: Casting Total + Penetration Bonus - Spell Level

ArM5 p.160:

"However, the target number for the spellcasting roll is the spell's level divided by five." (The "spell's level" being the target spell for Wizard's Communion, not the level of Wizard's Communion.)

I can locate no portion of the text of Wizard's Communion that even remotely suggests that it changes the target spell's level in any way. The altered target number to cast the target of Wizard's Communion is not the target spell's level. Therefore, Wizard's Communion can have no effect on Penetration per the RAW of both the magic rules and the spell's description.

I went back to ArM4 on p.158, and it is even more specific:

"[...] and the penetration of the final spell is either the spell level, or the highest Penetration total rolled by a participant, whichever is higher."

Again, it is the target spell's actual level, not its modified target number to be cast due to Wizard's Communion being used on it.

In ArM5, five magi get together to use Wizard's Communion on an Aegis of the Hearth level 50 (one of magi personally knows that spell) who each know Wizard's Communion at level 20, for a total of 100, double the level of the Aegis of the Hearth. The target number to cast the Aegis of the Hearth is 10. The primary caster has Rego 25, Vim 25, Artes Liberales 5, Philosophiae 5, Aura 5, and rolls 5 for a casting total of 70, easily beating the target number of 10. The primary caster's Penetration is 2.

70 + 2 - 50 = 22 Penetration Total

Thus, per the RAW, Wizard's Communion had no effect on the Penetration Total.

I must ask why people are treating the "target number for the spellcasting roll" as an indication that somehow the target spell's level has changed? Because everything I am reading on this forum says lots of people are treating it this way.

Note: In ArM3 and ArM4, both spells make it clear that the target spell of Wizard's Communion can be cast from a text, thus giving a big reason to use Wizard's Communion: in order to cast spells of higher level than the magi of a covenant can even learn (the ArM3 spell description says exactly that). ArM5 removed that capability from Wizard's communion, making it nearly useless as it only adds pointless risk now. If there was some type of intention to have the ArM5 version affect the Penetration Total, the RAW does not indicate it anywhere I can locate.

It could be written clearer, I suppose, but the "Spell Level" used for the Penetration calculation is the reduced "Spell Level" provided by the Wizard's Communion. The Penetration is meant to be how much the Casting Total exceeds the target Spell Level (+ bonuses). Wizard's Communion reduces the target Spell Level for casting so increases the Penetration. So, the Penetration Total is:
70 + 2 - 10 = 62.

The rules are different in ArM4 for lots of things. Especially Penetration.

There are many different operating (emphasized!) models for how Penetration (and AotH) works - when it's necessary, when it's not, and exactly how to figure it in any given situation.

To say that one entire model is "100% canon" is pretty ballsy, for just such reasons as you are suggesting. There always seem to be examples or sections of the RAW that contradict one interpretation or another (or could contradict, depending how they are read).

Personally, I cringe at the suggestion that a ward needs to penetrate to be effective - but you know what? Since I'm not playing in any Sagas that use that rule, and no one who insists on that rule is playing in my sagas, it just doesn't matter! :wink:

That said, I think the Aegis article you mentioned is pretty close - certainly close enough to work 99% of the time, and it appears self-consistent within itself. And that last is what's most important - that any SG (who wants to dive in to the deep end of this topic, ahem) has a consistent and workable model, for themselves and their Troupe.

(Some SG's use older Edition models or understandings to spin off of, some don't. Some remember earlier rules and are completely "wrong" by 5th ed RAW - but they still have fun, and their model still works for their Saga. But nothing says that a statement in an earlier edition hasn't been changed to one degree or another, or just scrapped completely. If you want to understand "5th ed qua 5th ed" then stick with that and only that.)

Me too. Before I had come across the topic in question, I had never even thought it an issue. But apparently it is.

When I read the topic I mentioned in my first post, I went searching for previous topics and found some on the Aegis/Penetration and on the Wizard's Communion.

Posters were talking about using Wizard's Communion on Aegis of the Hearth to gain extra Penetration, and I could not determine why. I still can't.

Adding to my previous issues with Wizard's Communion:


"Muto Vim (p. 159): Add the following paragraph to the end of the general description: "A Muto Vim spell, like any other Muto spell, can only change its target for as long as the Muto Vim spell is in effect. Thus, its duration should normally be at least as long as the spell that is its target. The spells below have a duration of Momentary, but versions with longer Durations can be invented as normal."

Even assuming a complete re-write* to the canon Wizard's Communion to allow it to affect Penetration (it can't at all as it stands), the canon version also has a duration of momentary. Anything it did to the year-long Aegis of the Hearth would cease, at best, a few seconds after Wizard's Communion was cast. A version with a duration of year would have to be a ritual itself. So, if you want to cast a Aegis of the Hearth 30, you need a minimum of 60 levels of Wizard's Communion Ritual learned by the participating casters, so I am going to hazard a guess that this requires six pawns of Creo/Vim vis and another twelve pawns of Muto/Vim vis. Each covenant's annual protection festival just got a lot more expensive.

The inability of Wizard's Communion to have any effect on Penetration (and a general overall uselessness) appears clear to me, and so I was thinking there might be some other rules I had missed. Which is why I had posted this topic.

As far as Aegis of the Hearth's effects needing to penetrate, I'm personally against the idea. As far as I am concerned, requiring it rips out half the value of the Aegis, but that's another issue. I have been working ideas on both sides of the issue for days and still haven't come up with anything I really like, and is why I haven't posted anything else, much as I wish to lead a knee-jerk crusade against Penetration in this case.

  • This is what I have on a re-write to Wizard's Communion so far:

Muto Vim General Wizards Communion
Range: Voice, Duration: Variable, Target: Individual (Ritual)

A special product of a pair of researchers from House Bonisagus and House Guernicus, Wizard's Communion has spread throughout the Order of Hermes. It is part Hermetic Magic and part Mercurian ritual. It was the result of a Hermetic Breakthrough that many felt was Major, but was ruled Minor by Notatus, the Primus of House Bonisagus at the time. It has effects that are not strictly bound by the standard spell guidelines. The primary effect of the breakthrough comes in the chameleon nature of the spell's attributes. The duration of Wizard's Communion is the duration of the spell it is targeting, and if the target spell is a ritual, so is Wizard's Communion. The lab texts of the research were published, but due to the effects of both authors writing portions of it in completely different styles with less than perfect clarity and contradictory statements, no one has been able to duplicate the breakthrough, or even use it to further their own research.

Wizards Communion functions as an enhancement of Wizard's Boost, it targets another Hermetic Magic spell, and increases its power. A group of magi assemble with one as a leader and the others as followers. The maximum number of followers is equal to the leader's Magic Theory score. All participants must know Wizard's Communion. The combined level at which all participants know Wizard's Communion must be double the level of the spell to be targeted, or Wizard's Communion cannot be cast. The leader must personally know the spell to be targeted, and will be the one who casts that spell. All participants must cast Wizard's Communion successfully. The leader must make the standard concentration roll for casting a Muto Vim spell at the same time as another spell: Intelligence + Concentration at 9+. If the spell to be targeted is itself a ritual, then the leader must decide if each follower is also a part of that ritual (important for Aegis of the Hearth). If Wizards Communion is a ritual, then because there are two rituals underway at once, all participants must also make a Stamina + Concentration roll with an Ease Factor equal to the magnitude of the spell to be targeted (divided by ten + 2).

Every two followers, or fraction thereof, casting Wizard's Communion adds one botch dice to any botch rolled for all participants. This value is fixed once Wizard's Communion commences. If any followers drop out of the ritual, the extra botch dice total does not change.

If any spellcasting or concentration roll on the leader's part botches, the entire operation fails and all vis used is lost. If any follower botches a casting or concentration roll, they are removed from the spellcasting operation and the final bonus provided is reduced by that spellcaster's absence. For each follower dropped from the ritual, the leader must make another concentration roll of Intelligence + Concentration at 9+.

For every follower casting Wizard's Communion, a bonus of five levels will be provided to the spell that is targeted. The troupe may make recommendations about how they want the bonus to take effect, but the storyguide makes all decisions (just as in Wizard's Boost). The most common effect is to increase the casting total of the spell beyond what the leader rolls for the purposes of enhancing Penetration. Less common effects including boosting range and duration. The least common effect would be to boost the target. The descriptive effects of the spell, or other factors, are never boosted.

If vis is used to boost the power of Wizard's communion, that amount is used to increase the bonus for the spell to be targeted noted above. Each follower may independently contribute vis for boosting, although if every participant did this at maximum, it would become expensive. If the spell to be targeted is a ritual, then the leader must pay that spell's vis cost and cannot contribute to vis boosting on Wizard's Communion or paying its ritual vis cost. If Wizard's Communion is a ritual, the followers must pay its vis cost (limiting capacity for vis boosting).

For reasons unknown, Wizard's Communion cannot be mastered. [I am thinking of having this type of restriction on all the classic part-Mercurian Hermetic spells, primarily to avoid the Spell Mastery on Aegis of the Hearth with Magic Resistance option trick for easily getting around an Aegis; assuming Penetration is being used.]

While the above makes Wizard's Communion useful, it is also pretty complicated and alters vis economies for covenants. All just to get it to be able to add Penetration to Aegis of the Hearth so this standard defense spell can have a hope of functioning as written. Hmmm. Some further thinking is required here.

Too complex for no gain. Richard Love's answer is a much better solution.

There was a ReVi/MuVi rewrite discussion earlier. I bet most saga are close to that already.

BTW, we don't play with penetration even for wards. WC is used for direct effects.

I'm with Richard Love on this one too. If WC doesn't help with penetration, it doesn't have much use in the game. I never really considered any other way for it to work, to be honest.

Would you be kind enough to provide a link? I'd be most interested to see this discussion. :slight_smile:

Here was the discussion about editing the errata :smiley:

I think that RAW do claim Wards must penetrate (HoH:s pg 113).

Now assuming that Aegis is a ward (I know this is a hotly debated topic), then WC would make it a lot more beneficial.

A casting total of 25 would have a much better penetration on a level 7 spell then a level 25 spell and 4 magi all WC'ing to cast a level 25 AotH would make it a level 7 spell not a level 25 spell. An 18 point difference is pretty impressive.


Yes, and I think it is one of the interesting things from "aegis must penetrate" opinion.

Thanks ExarKun, a lazy search didn't find it yesterday.

This is actually irrelvant as to whether the Aegis needs to penetrate.

Aegis is a spell. The RAW is that spells need to penetrate to have their effect, baring explicit text that says otherwise for that particular spell. The Aegis lacks such text, therefore it needs to penetrate (according to RAW).

Wards also lack that text, but that is a separate issue.

Pilum of Flame also lacks that text. As do almost all spells described in the corebook or the supplements.
Yet we don't see people arguing that a PoF doesn't need to penetrate, applying instead the general rule. Why would it be different for Wards and/or Aegis?

Because every other spell has a specific Target, a Target that can be sensed at the time of casting - and wards and Aegis do not. Their Target is the thing warded, not the thing warded against. Therefore (to some minds) they have a different feel from any other spell, and so invite a different approach, a different mechanic.

Not by the rules, no - but as a paradigm, if one not supported by RAW.

For most small MR's, there is no difference. But for larger MR's, what it means is "all or nothing" - there is no "penalty" from an insufficient Aegis, because no matter how big it is, if it's not big enough to penetrate then it's has no effect at all. Aegis 50 vs a MR 70 dragon? Sorry, no luck, nice try, thanks for playing, but Aegis = 0, kkbb.

And that just doesn't feel right, despite the lack of any explicit text to the contrary. Ysmv.

The basic issue has been pointed out repeatedly: it is easier to kill/destroy something than to ward against it. That does not feel right. Not to me (and others) at least.

WC is a good way to achieve decent penetration. Every apprentice and his mother has it around here.


For the wards, isn't that a consequence of the incomplete integration of columbae magic into hermetic?

The "aegis must not penetrate cause" main argument is, for those for whom wards must penetrate without debate, that it is a breakthrough.

I must confess that when I started playing, the ASG IRL said it must not penetrate, then I discovered the spell and as a breakthrough it seemed right. Should I start playing now, I would think it must penetrate.

Exar, who is currently thinking about shifting from "must not penetrate" to "must penetrate" in his online saga.

One could look at it like "stone skin", but against magic rather than physical damage.

The spell doesn't have to penetrate the attack, because it is not cast on the attack. It has to penetrate the target protected. Once in place, it simply works against all comers.

That's the paradigm. And that doesn't need "explicit text to the contrary", because by definition it works differently from typical spells - the effect is already in place, and the incoming effect is what needs to penetrate, not the other way around.

(Or would you have a protection effect like "stoneskin" need to penetrate against any magical direct-damage attack that then comes at it, before protecting the target? If so, then nm.)

So you say, but this is tends to be false in play. Whether it is easier to Ward or Destroy is very context dependent.

For wards you don't need to sense the thing(s) you are warding against. Which makes wards much more convenient if you a) are anticipating an ambush, b) are worried about things that are difficult to sense, such as demons, and/or c) are a magus who has much better things to do than guarding some location against a bunch of irritating faeries (for example).

Personal Wards can also be much, much better when you have hordes of relatively small creatures to deal with.

In fact, I think that I would almost say that the only time it is actually better to Destroy is when the magus is faced by a hostile single, relatively powerful critter.

So, sure, there are times when it is easier or better to Destroy critters. But there are also plenty of times when it is much easier or better to Ward against them.

From a game balance point of view (not that I really like arguments based on such a fiction) because Wards are actually usually better they should be harder to cast than Destroy...

I guess you have never had player characters with Hermetic Boundary artillery boosting 100+ penetration... In other words, not false IMS... :confused:

YMMV, but IMO the single powerful critter is the one that I think should be warded by the characters instead of turned into a pile of ashes. It is supposed to be the creature that is supposed to give you trouble, and that you trap instead of kill because it is too powerful for you to deal in other ways. You might want to trap it instead of killing it for sure, but supposing an hostile creature you want to deal with, killing should not be easier. We do not like it, at least. The fact that by the RAW the big guy looks like the walking vis stack ready to be collected and the small creatures are the ones being problematic makes me put a blank face, really.

IMS hordes of small creatures do not tend to be that common in any case. We prefer one or 2 supernatural dudes around instead of hordes. Otherwise we feel like we are playing in Faerun, not Mythic Europe.


If this is the argument why wards shouldn't need to penetrate, by this reasoning a Flambeau with Greater Immunity to Fire could use that level 50 R:Personal CrIg spell and walk up to something with magic resistance of 500 and penetrate with ease. Wards and Aegis are not alone.