This question has been asked before, but I only found some discussions on this topic that are over a decade old, before the latest rounds of rules clarifications and erratas.
Could one develop a MuVi spell that could boost the Penetration of a target spell? Say by +5?
Personally, I would tend to say yes. Because, honestly, there isn't much difference between:
Casting a MuVi spell that add +5 to the Penetration Total of a standard Pilum of Fire (which deals +15 damage),
Or casting Wizard's Boost on a level-15 variant of Pilum of Fire that only deals +10 damage (which Wizard's Boost will increase to +15).
Conversely, I'd tend to say no. It's not a parameter. It's not an aspect of the spell/effect (which is the entity you're targetting with Muto), but rather an aspect of your of ability to interact with magic.
Do I know? No. And I could certainly be persuaded, though I cannot promise that it would be easy.
One of the MuVi guidelines is to increase the power of a spell by a magnitude. I can think of no reason why that power increase could not consist of increasing the penetration of the spell.
Totally change a spell of less than or equal to half the (level + 1 magnitude)
of the Vim spell. This may change the Technique, Form, or
both of the target spell, and needs no requisites for those Arts. The
Vim spell affects the structure of the spell, not the things that the
spell targets. A change in power of up to two magnitudes is a total
change. Any greater change requires either Creo or Perdo to create
more magical energy or destroy some.
Adding 10 to Penetration is considered a change in power of 2 magnitudes in this instance, from what I can understand.
Tangentially related: what would it take to boost the power by three magnitudes (in addition to the Creo requisite)? It's explicitly possible (by what's written above), but I've never seen anything suggesting the actual mechanics.
Given that 1 magnitude requires, roughly, a 1:1 spell-to-metaspell level ratio; that 2 magnitudes require, roughly, a 1:2 spell-to-metaspell level ratio ... I'd be tempted to say that if you roughly triple the basic spell's level with the metaspell, you can add three magnitudes, if you roughly quadruple it, you can add four, and so on. Of course, some people do not count 1-2-3 but 1-2-4 ...
My character has the following spell - which is by the way a nice result of an experiment:
Safe Way of Overwhelming Penetration for the Vim Spell
Mu(Cr)Vi lvl 30
R:T; D: Mom; T:Ind;
Makes a Vim spell you will cast to have an increased Penetration of +15. The target spell must be lvl15 or lower. See MuVi GL in ArsM 159.
Experiment: Minor Side Benefit: If this spell cast succesfully the modified spell has one less botch die to roll (if Botch is needed to be confirmed).
(Base 25, +1 T, +0 req. Creo)
The experimentation makes the example a bit less clear but ... if I understand correctly, in terms of level of the metaspell necessary, you are saying that adding 2 or 3 magnitudes is essentially the same - the only difference being that one needs a Creo requisite, right?
We discussed the question of Muto Vim spells, and we followed this logic:
You can affect spells not greater than lvl25 without needing a Ritual.
You have to roll stress die for Concentration with a potential for Botch.
In a stressful situation using MuVi metamagics mean that you have to roll stress dice 3 times - 1 for MuVi spellcasting, 1 for Concentration, 1 for the affected spell.
Those together are enough restrictions and danger on the long run not to spam this kind of magic. Or the PCs can spam it, but bumm, here goes the Botch
That's why we didn't want to go with a formula of 1:3 or 1:4. That would add power only to weak magics, but in this way we use PCs can consider to play big, and fail big in critical times generating more rare, but more spectacular happenings.
But for clarity here on the forums, MoH is most certainly canonical. Not only that, its very purpose is to show players different spells and enchantments they could do canonically.
And yet it's the most logical ruling there is. You can, with a given Muto Vim spell, add a magnitude of effect to your spell without lowering your penetration. Why shouldn't Muto Vim be able to, instead, add penetration to a similar degree, especially knowing the magnitude boosting spell is of lower level than the equivalent penetration boosting spell? This is especially true with enchantments, where you're literally including your penetration in the enchantment design calculation.
Yup. To add to this, we've already seen that it can through Wizard's Communion and Wizard's Vigil. It can add far more. So if we already know MuVi can boost penetration and more since the core book, is it really so questionable to let it boost penetration?
Exactly why I do not like it to be designed in MuVi. The core rulebook already shows how to improve penetration using MuVi.
I could have prefered CrVi where it creates a shell that carries the other spell in using its own penetration or PeVi to break the resistance down just as the other spell kicks-in.
It shows one way one can, indirectly, improve penetration with MuVi.
That sounds far too complicated. Especially since one would have to invent new mechanics for how it would work - as opposed to MuVi where "increase power" already exists as a guideline.
Don't know what you are talking about. Ars magica is built to handle creating new guidelines et and effects. Actually takes me a few seconds to draft the exemples:
CrVi 30 - Voice | Mom | Ind | - Piercing Lance (Vim)
Creates a Shell of Magic that carries a formulaic effect of up to level 25 through magic resistance. The victim needs to resist this effect’s penetration 1st instead of the one of the spell being carried. If resisted, the shell is nullified and the original spell’s penetration is tested. As usual, this effect needs to be cast in cooperation in order to be effective which means that a mastery in fast cast is highly recommendable. There are 10 versions of this effect, one for each of the hermetic forms.
(Voice +2 | Mom +0 | Ind +0 | Base 25 (general +1))
PeVi 20 R:Voice, D: Mom,T: Ind - Momentary Lapse of the Parma
This spell nullifies the Parma Magica of the target for but a moment allowing one round where the resistance is lowered. The target’s Parma Magica Score must be less or equal than (29 + stress die) divided by 5. Obviously, this spell is only really useful for attacking other magi. Thus, some tribunals may view magi who are known to have invented this spell with suspicion but it is less controversial then the one that completely dispells the Parma. This effect has been used to help injured Sodalis that are unable to lower their Parma. Like all spells, this spell must Penetrate to be effective. Higher-level versions of this are possible for attacking targets with greater Parma Magica scores. Note that this spell uses the Perdo Vim guideline, which dispels magic effects of a specific type (ArM5, page 160). Parma Magica is an example of a magical effect of a specific type, which all Hermetic magi are familiar with. This is why Wind of Mundane Silence (ArM5, page 161), which dispels all magical effects, is effective against Parma Magica. This spell does not dispel Magic Resistance generated via other sources, nor is this spell effective against any other sorts of magic.
(Base 4: dispels magic effects of a specific type of the same level or less + 4 mags + stress die, +1 Touch)
Ok... the Perdo one is not exactly a penetration enhancement but Perdo already kill Parma...
Suppressing Parma, for a moment, would be ReVi and there is already a guideline in HoH:S p129 (errata'd text copied):
Rego Vim
General: Sustain or suppress a spell or spells of a specific type cast by another with level less than the level + 2 magnitudes of the Vim spell. Examples of specifics types include Hermetic Terram magic and Shamanic spirit control magic. This guideline may be used to target the spell itself or the caster of the spells.
