Anti-magic and Perdo Vim: so what's the problem?

So, I've been messing around with the Perdo Vim rules, and it seems that they're the go-to TeFo for anti-magic. However, according to the rules, it's Rego Vim that will likely be the place where integration of Parma will occur. OK, that sounds fine. However, it's pretty easy to design the following with PeVi:

So... some issues here seem to be that it would affect magic going both ways, and that it's at a 1/2 level of effectiveness. Is this simply a known issue? That is, this is the "current state" of anti-magic warding, and that it's assumed that there's some better version, buried in ReVi Magic Theory? Because, honestly.... this seems pretty good. I'm not seeing any restriction against Realms here (Serf's Parma), so it's not like you need to learn 4 different versions. And it cancels out based on magnitude, so penetration simply isn't an issue.

So maybe the issue is really the original issues: it's at 1/2 magnitude, and it cancels out things going both ways. From a Wizard's War perspective, the 1/2 magnitude thing really isn't an issue: it's all lvl 5-15 effects, anyway. So I guess it's the fact that this simply isn't as GOOD as Parma or Aegis, would be the issue. It's indiscriminate, and thus prevents you from casting out your own techniques. (Although I would imagine that could be taken care of via alternate spell design - ie, +1 complexity to have it only work in one direction, or something.).

Are there other issues that I'm not seeing for this?

PeVi with a duration isn't ongoing dispelling, it's basically supressing - which has its own ReVi guideline, so PeVi with a duration simply doesn't work for this.

A common misconception: Duration of effect doesn't mean repetition of effect. The effect affects the targets once for its duration. A ReVi effect wards it targets for x duration, while a PeVi effect removes targeted effects permanently when cast with Momentary duration or removes them for x duration.

I'm pretty certain you do need separate versions for each realm.

If somebody crosses the circle carrying active effects, then the proposed Circle of Protection Against Magic will need to Penetrate that person's Magic Resistance in order to dispell those effects.

This is a significant problem. You can't use it like a cookie-cutter, like you can with Parma to deal with mundane problems --- with Parma you can share it with your grogs, then forcelessly cast some sort of "immolate area" spell, which will burn everyone except yourself and your grogs.

It doesn't seem to stop somebody who merely walks across the circle from then casting effects within the circle.

In play, in my saga, many magi who are 30-40 years post guantlet have Parma Scores in the 5-7 range. To get equivalent protection from the proposed Circle...against Magic you are beginning to look at a ritual, and needing to be a serious Vim specialist to invent/cast the effect (and it will also take ages to cast if it's a ritual).

Having said all that. It is not a bad spell. It's a circle version of Wind of Mundane Silence.

This is probably good enough most of the time.

If the effect you are removing has a shorter duration than the PeVi effect, then it won't come back when the PeVi effect expires. Also, if the original targets have made themselves absent in the interim, then it doesn't matter if the "dispelled" effect comes back.

I've noticed that when magi get into the 30+ bracket, having Parma scores in the 5-7 range and penetration scores of similar ranges means:

  • you can rely on your parma to deflect a LOT of crap.
  • against anything that represents a proper threat to a magus of your power level, you can assume your parma doesn't exist - and that any effect with a similar behaviour will likewise not exist.

Where PeVi is interesting is it targets spell level, not spell penetration. It's almost the opposite of Parma in this regard: parma is reliable for shutting down high level spells with low penetration, while PeVi is better for shutting down low level spells (with high penetration).

Effects that negate the result of the spell rather than the penetration of the spell make for better combat options. For instance, if all your grogs have a ward vs. gale-force winds then you can drop gale-force winds on the battlefield with the penetration cranked right up to eleven and not worry about friendly grogs in the way.

This is mainly what I was thinking - that Wizard's War effects are usually in the level 5-20 range, which is the near-maximum range for non-ritual antimagic wards. (Lvl 50: Base lvl 35, R: Touch +1, T:Structure +3, D:Moon +3 = lvl 18+die of antimagic)

(EDIT - or I suppose you could go with Concentration (+1) to make it easier, if you had the appropriate Maintain the Demanding Spell effect. Or, use the Warding virtue from the Ex Misc warding folks to just carve it on the door.)

Hm. I was interpreting the comment as being that a non-momentary perdo effect (such as, say, a Circle/Ring) doesn't do anything to a target that isn't inside the range of its original effect - at best, it only cancels out spells that are in the circle ring at the time of casting.

However, I was under the impression that circle/rings didn't work that way - that they continued to affect anything (ie, basically pulsed once a turn) on anything that moves within its boarders, until the ring was broken. It lounds like Toa is saying that is not the case. Toa, if I have interpreted you correctly, can you give a reference for that?

Indeed PeVi is the inversion of Parma. Parma is weak against little effects. PeVi cleans them right up. Anyway you certainly could do some sort of invested item to dispel incoming small effects. It would be

See incoming Magic - ImVi 39
R: Per D: Sun T: Vision
Detects magic that will target the bearer of the item.
Base 5+4 vision +2 sun +4 constant

Counter Cantrip - PeVi - 46
R: Sight D: Mom T: Ind
Whenever the item detects incoming magic this effect is triggered. If the effect is less than half (20+stress die no botch), the incoming effect is dispelled. Only works on magic. The wielder can also dispel effects manually. Her own magic, and that of her familiar is not affected.
Base 15+3 sight +10 unlimited uses +3 linked trigger +3 list of people.

Any spell less than level 10 fizzles. It costs 9 vis to enchant and 9 to open so it isn't cheap, but its pretty cool. Arguably this could be touch range, dispelling anything as it hits the maga, but before it has any affect. Not only would this take 15 levels off the detection effect, and 10 levels off the counter effect, it would also allow it to go into the familiar bond. So you and your kitty are safe. Adding two magnitudes increases the dispel by one magnitude.

Side note on monsters: This works against other magi. You can lend it out during a Wizard's War. (And then bring the person up on charges if they break it.) Not so much against creatures; their effects have a level equal to their might. Mr. Dragon's 1 might cost fire breath? That's a level 50 effect. With 45 pen.

Side note on Wizard's Wars. You win if you get an arcane connection and have a kill spell. By kill spell I mean something that will drop the target, at least with enough castings and has a range of arcane AND is mastered. The last bit is important. You want to know how many times it takes to get a roll of 80 on average? 10,000. Or a solid day of casting on a stress no botch die. 160 averages a about ten days. Your fancy 20 parma and 50 in the form? Not gonna cut it.

Hm... So, Rego Vim's got general wards and (potentially) Parma.
Perdo Vim has Anti-magic.
Muto Vim has wizard's Fork and the redirection magics (I think).
Intelligo Vim...doesn't have anything.
Creo Vim...probably should have something, but hasn't been explored by the Order as a whole.

How about the following?

The idea being that CrVi can create magical "shells" that, on a magical level, look identical to something else. So that if someone, for example, casts a Sight-based spell on a target, and the target has this effect running nearby, the spell will be redirected towards it. (Kind of like the inverse of Wizard's Sidestep.) The +1 complexity represents the fact that the target needs to look MORE like the target than the target actually does, in order to attract the spell.

This would, weirdly enough, be MORE effective as the range of the target spell goes up. (Incredibly useful against Arcane, Decent against Sight and Voice, almost pointless against Eye or Touch.)


You might wish to discuss with your troupe first, whether there is a way an item can detect magic that "target the bearer of the item" - or, in other words, magic to ascertain Targets of magic not yet completed.

  • First, your troupe needs to determine, whether the Target of an incoming spell can be determined with an InVi effect at all, before the spell struck.
  • If so, the box on ArM5 p.158 hints at an addition of three magnitudes at least to find this out just for an Hermetic spell.
  • But even then, the analysis of non-hermetic magic to a sufficient detail might - by troupe decision - require more specific magic effects.
    Typically (see ArM5 p.83), Hermetic spellcasters deflect low level spells they are aware of by fast-cast defenses, relying on their own analysis of incoming magic to pick the right response, which may indeed be a PeVi spell very often. Formulaic PeVi spells - e. g. like the effect of your Counter Cantrip - might be mastered for fast-casting especially, to be used in this kind of defense.


This is a brand new CrVi Guideline. To sell it to your troupe, you might compare it to the third general CrVi Guideline in the box on ArM5 p.157 "Create a magical shell which gives false information about the target to Intellego spells with levels less than half its (level plus one magnitude).", and hence reduce the level of affected spells further.


Whoop - yep, that's the one I was basing it on - I thought it was (mag +2)/2 - so adding in a +1 complexity would push it down to (mag+1)/2. (Again, serf's parma - my computer's got a loose CPU, so I'm posting from work for the next few weeks while it goes back to Acer.)

The big difference between the ArM5 Guideline and yours is moving from "gives false information about the target to Intellego spells" to a far more general "Creates a magical duplicate that attracts all spells cast at the target".
Your troupe could simply forbid this generalization, period. Or they could request a further reduction of affected spell level - perhaps once again halving the affected level in the new Guideline to "level less than a quarter".