Mastering Muto Vim: Clarifying Metamagic Rules in Combat and Beyond

After delving into the rules for Concentration and Muto Vim, I’ve encountered several questions about how these mechanics interact, particularly when casting multiple MuVi spells on a single spell. These questions touch on the Ease Factor for Concentration rolls, the timing and number of turns required, and the use of metamagic in combat scenarios. While similar discussions have taken place before, the definitive version and the many erratas on Muto Vim guidelines make this a timely topic to revisit. Below, I outline my understanding of the rules, explore some hypotheticals, share points of confusion and conclude with my own interpretation:

Concentration Overview

Concentration and Distraction: According to Chapter 7 (Hermetic Magic), Concentration rolls are required only when the caster is distracted. For example

  • Walking while casting is considered a distraction.
  • Combat typically introduces distractions that necessitate rolls.
    If you are concentrating on a spell there are more cases where you need to test for concentration:
  • Testing is needed for "Casting another spell" or "Maintaining another spell."
  • However, if the spell’s is designed to do a certain action, that action does not interfere with the concentration

Muto Vim Overview

MuVi Concentration:

  • Casting both a MuVi spell and its target spell requires a special Concentration roll (let’s call it the "MuVi Concentrating Test"), which is easier than standard rolls.
    Timing and Duration:
  • MuVi spells interfere with the target spell during its casting, so both must go off simultaneously.
  • For non-ritual spells, a Momentary duration suffices for the MuVi spell.
    Casting on Others:
  • MuVi can be used on another mage’s spell, either with fast-casting or cooperation.
  • two diferent magus can coordinate to cast two MuVi spells on a sigle normal spell

Hypoteticals and confusion:

  1. Scenario: Casting a Concentration-Duration Spell and a MuVi Boost in Combat
    Interpretations:
  • Only the MuVi Concentrating Test is needed, as per MuVi guidelines.
  • Since both spells are cast simultaneously, the magus is not considered "concentrating" on the first spell while casting the MuVi spell, and only the MuVi concentrating test is needed.
  • Both a MuVi Concentrating Test and a "Casting another spell" Concentration test are required, since the MuVi boost comes after the concentration-duration spell.
  1. Scenario: Casting a Momentary-Duration Spell with Two Different MuVi Spells in Combat
    Interpretations:
  • This is not allowed; the guidelines permit only one MuVi spell to be cast with another spell per turn.
  • The second MuVi spell would target the first MuVi spell rather than the original spell (e.g., Normal Spell <- MuVi 1 <- MuVi 2), so you need to Multi-Cast or Target: Group (see below) on the Muvi 2 to apply to the normal spell.
  • This is possible, but the magus must make separate MuVi Concentrating Tests for each MuVi spell.
  1. Scenario: Fast-Casting a Momentary-Duration Spell with a MuVi Boost
    Interpretations:
  • The magus must fast-cast both spells, requiring two fast-cast rolls and incurring the penalty for multiple fast casts in a single round.
  • The magus fast-casts only the normal spell, and the MuVi spell is automatically cast alongside it.
  1. Scenario: Casting a Mastered Multi-Cast Spell with a Wizard's Boost Affecting All Castings
    Interpretations:
  • This is not possible; MuVi spells only affect a single instance of a spell.
  • It is possible if the Wizard's Boost has a Group target (supported by precedents in MoH).
  • It is possible if the Wizard's Boost is also Multi-Cast, with each casting affecting one instance of the normal spell.
  • Both of the above interpretations are correct, where it can either be target: Group or Multi-Cast.

My Interpretations and Thoughts on the Scenarios

  1. Casting a Concentration-Duration Spell and a MuVi Boost in Combat
  • Preferred Interpretation: The second one—both spells are cast together, and the magus is not considered "concentrating" on the normal spell while casting the MuVi.
  • Alternative View: The third interpretation could also work, but it makes life unnecessarily difficult for MuVi specialists who aren’t masters of Concentration.
  1. Casting a Momentary-Duration Spell with Two Different MuVi Spells in Combat
  • Preferred Interpretation: The third one—it’s possible to cast two MuVi spells with the appropriate MuVi Concentration rolls for each.
  • Alternative View: The second interpretation is also plausible, but it would significantly impact the effectiveness of a MuVi specialist, demanding even more formulaic spells and/or mastery, potentially reducing their strength.
  1. Fast-Casting a Momentary-Duration Spell with a MuVi Boost
  • Preferred Interpretation: The first one—the magus must make separate fast-cast tests for the normal spell and the MuVi spell, with penalties for multiple fast casts in the same round.
  • Alternative View: The second interpretation could be valid, but leads to absurd scenarios when combined with cases like multi-casting or multiple MuVi spells—all with just one Fast Cast test.
  1. Casting a Mastered Multi-Cast Spell with a Wizard's Boost Affecting All Castings
  • Preferred Interpretation: Both interpretations (second and third) are valid. There is precedent for this in MoH (even though that book is somewhat controversial), as well as in other forum discussions.

In summary, my goal with this topic is to clarify my doubts as I develop my own Mutantum gifted Mercere character and, in the process, assist anyone else who shares the ambitious (and slightly mad) idea of creating a Muto Vim specialist.

There's two ways to Muto Vim IIRC:

  1. The Simpler way: You cast the MuVi one round, with Momentary duration, and the next round you cast your spell to be modified.
  2. The Harder way: You master the MuVi for Fast Casting, and can Fast Cast the MuVi, and then normal cast the spell to be modifed. (Rememebr that fast casting reduces your Casting Total by 10.)

Would you mind telling me where did you get/found these rules?

The problem I see with the first way you described doesn't fit the description on the Muto Vim guidelines:

"Muto Vim spells work by altering the magical energies that create the spell as it is being cast. [...] a Muto Vim spell must have a duration at least as long as the casting of the target spell"

Which suggests that the MuVi spell is cast at the same time of the normal spell, not before.
The only exception would be if it's duration were concetration, but none of the canon MuVi spells provided are so i don't think that was the creator's interpretation of the rules.

And if the MuVi must be cast at the same time the second way you described is absurd, since it would demand fast cast for every Metamagic, being impossible to cast it otherwise

A momentary spell lasts but a moment - in the cases of some spell, that can be up to a combat round. So yes, casting a Muto Vim spell one round and the regular spell the next one is fine.

IIRC the Hermetic Magic chapter - Fast casting part explains that you can cast more than 1 spell in two ways:

  1. Cast your normal spell when your Initiative Total let's you. After that you can "react" to something with Fast casting spells .

  2. Try to Fast Casting first, but if you miss the Init for Fast casting or your Casting Total is too low you can't cast the Fastcast spell and also missed you normal spell option for that round.

(Maybe it is cleared by Errata or Lords of Man)

This part is incorrect. The duration of the MuVi must last through the casting. So the MuVi must be cast before the spell to be altered and not end until after the spell to be altered is finished being cast.

Itzhak Even is correct, though you could fast-cast the MuVi and then fast-cast the other spell, too. The error I just noted explains why this works.

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The question i get when you cast the MuVi in the round before is the description on many MuVi spells: "you cast this spell on another spell while the other spell is being cast", which assumes the other spell is already being cast.

If you cast MuVi in one round and the normal spell afterwards what is the target for the MuVi? Is the normal spell already considered casting? Is the target the future spell which doesn't exist yet? Do you "hold" the MuVi of momentary duration until your next turn?

All of these answers seem against many hermetic rules and feel really wrong from a RP perspective, where you need to spend 2 rounds to cast a funny spell just because you chose the worng character, while the other magi can do funny things in a single round.

But what is the target of the MuVi spell if you cast it before the spell? Can you cast a spell on a future target? And what about the description of the metamagic spells: "you cast this spell on another spell while the other spell is being cast", which assumes the other spell is already being cast. Is the target spell already considered being cast on the round before?

In feels contraintutive and really anti-hermetic, besides being overly punishing for any player that wanted to do a MuVi character

Yes, David said roughly "there is some blurring of the lines [with the Target] so that MuVi is possible at all." The Target might be thought no so much as the other spell, but as the spell-casting process; it's really the other spell as it comes into existence, but that way of thinking can help. This is why there is a Concentration roll when you're doing it on your own spell. That lets you time the end of this with the coming effect to be altered so that the Target at least essentially exists.

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This question I don't understand. Momentary spells can last for just an instant, but they can also last a full round. They can even last longer than a full round, but not much longer. Once you cast the MuVi spell, the timer on the Duration starts ticking. You need to get that other spell in right away.

Well if the correct interpretation is that you cast the MuVi on the round before than that is a really unsatisfactory answer, but oh well.

It makes no sense for even a MuVi specialist to learn MuVi for combat if it takes 2 turns to do something, unless you are really good at
finesse for fast casting (while also being good at concentration so that you can even cast the MuVi without problem), so off with that flambeau from MoH.

A new question that appears is then how long can you wait for the second spell. If momentary duration can be longer, couldn't you cast two of MuVi one after the other in two rounds (or even in one with normal+fast cast) and then the target spell? The argument against would be that itfeels wrong and momentary shouldn't last that long (even though the description is vague and doesn't set a time limit)?

And what about MuVi with longer durations? Could you stack every possible MuVi spell and when you want just spend it all on a target spell? (Yeah i know this sounds stupid)

I know that Ars Magica likes to be somewhat open with its descriptions, but sometimes i really wish they gave more elaborate examples, specially in such edge cases.

I don't see any reason to give MuVi intelligence, and normally you cannot delay spells, though there are tricks to cause such delays.

So, sure, let's say you cast two MuVi spells, one after the other. The first MuVi affects the second MuVi. Then the second, altered, MuVi affects whatever would come after it.

One of the important things with Momentary perhaps going a little longer than a round is that someone with Slow Caster can still use MuVi on their own spells.

Again, sure, stack some MuVi. The first MuVi affects the second MuVi. The second MuVi affects the third MuVi. Etc. I don't see how a longer Duration helps unless these are a pile of ritual MuVi effects.

Well don't worry about that, i have ample time and creativity to find uses during the holidays.

(Like thetering a concentrating MuVi with touch range on o rock and maintening the demanding spell ReVi. When i wanna use the metamagic on a normal spell I introduce the rock and end the duration of the MuVi with harnessed to time both (or more) spells and cast a normal spell with many metamagic on it)

There's a catch there. If you cast the MuVi on an item, then it will only affect a spell the item casts. Even investing MuVi in items doesn't work on your spells.

Even if it did, your MuVi will need to be able to affect a spell that's changed by the other MuVi spell.
Say you want to change the Target of a spell you cast, and also increase the guideline used.
Say the spell to be changed is 15.
One of the MuVi will need to be at least level 20, and the other at least level 25, because one change will increase it to level 20, and the second to level 25.

Does the rules for MuVi on magic itens apply to tethered magic (as in HoH:TL)?

If you tether a magic to an object it holds for the duration, and when a valid target comes within range the magic is cast.

On could argue that you can only MuVi with touch range your own spells, and as such a tethered MuVi would need to have a bigger range, but you could tether the target spell to the same object and as such it would cast both the normal spell and the MuVi.

That would be useless. The rock wouldn't touch the spell you're casting. Now, you could use voice, but...

Then, with Voice, it affects your ReVi. Might as well have just MuVi your ReVi yourself and used Touch.

No need to argue it. That is a core rule. And once the spell is cast, it's too late for the MuVi, so casting on the object doesn't get past this problem.

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Range Touch can only affect spells you cast, so yes.

If you Tether into an object, what range would you use? Hearing, Eye, and Sight don't work, because the object cannot hear, make eye contact or see.

And an object cannot activate two effects at the same time. You could make a Linked Trigger for the second spell, but without the MuVi activating it wouldn't activate, and to activate the MuVi, the object needs to activate the spell to be changed. Kinda stuck there. So that only works when you enchant both into the item.

You are using the rules for invested items, but tethering (as far as I'm aware) is a diferent thing, and since an object can touch itself, if you tether the targeted spell into the object the tethered MuVi would go off, and if the conditions for the normal spell are met it would also be casted soon after.

Edit: just understood the argument Callen made, so it would still not work..

Damn that is true, the MuVi would have to have a larger range....