The Creo animal guidelines contain a provision for creating a magical creature. The guideline is level 50 so you can't do a spell for less than level 55 because of range, ergo any spell must be a ritual.
But an enchanted device can produce effects of over level 50 providing that they are not ritual effects for any other reason aside from level.
Familiar bonds are enchanted as enchanted devices.
So if a magus who has an enchanted animal familiar, (I'm going to look at Ranulf as an example for reasons that should be obvious) what level would it be to transform a who is a might 15 magical animal into a might 35 fire elemental for duration concentration with the item maintaining concentration?
Muto animal base 25 allows an animal to gain some magical ability (an amazingly useful guideline for enchanting familiars by the way), changing an animal into an inanimate object is only a level 15 guideline. Should it be lower level to change a creature into a fire elemental than it is to crete a fire elemental from nothing?
The Creo guidelines say that a created creature can not have more might than the level of the final spell, but using that a "rule" rather than just a limitation to watch points us to the (I feel) problematic situation where creating a might 55 creature is no more difficult than creating a might 5 creature.
My first inclination would be Muto Animal with ignem and vim requisites base level 45 (Just one magnitude lower than creo animal) with 2 magnitudes for increasing the might from 15 to 35 (1 magnitude per 10 levels), and then the expected modifications of +1 magnitude for range touch, a possible magnitude for a large elemental, +5 levels for item maintains concentration, and a ew levels for uses per day.
This gives me a final level around 72. Does that seem like the most appropriate level calculation? How do you see it differently?
My basic inclination is to consider the effect independent of the target. That is, it can transform any animal into a fire elemental. So:
Mu isn't necessarily easier than Cr; in some ways it's harder. It also provides additional benefits, such as turning a sea monster into a fire elemental and watch it no longer enjoy its immersion in water so much. I'd use the same level.
The Might of the base creature is not relevant, since I can transform an ordinary sparrow into a fire elemental (or phoenix!) too.
So, that's base 50 plus 35 for Might.
Once we're here, why not add Co to the requisite list, so you can be fire elementals together when you want to be?
Hermetic Projects (page 126) states that a spell that creates a magical animal is always a ritual, and cannot be instilled in an enchanted device. I'd be inclined to apply the same limit to Muto spells.
Do you have a rationale for 1 level per might point? The Creo guidelines tell us that a spell can't provide a higher might than its level. But with a base level of 50 just to create a magical creature, getting a might higher than the spell level is already impossible. Above I used 2 might per level, I have no solid rationale for my take either, it just seemed to produce effect levels that were, to me, more believable than 1 might per level.
Because an extra magnitude for the corpus requisite and 2 extra magnitudes for target group don't compare favorably to just learning it as a spell.
From context this resrtiction is pretty clearly speaking about a spell that creates a magical creature with duration momentary. A spell that makes a creature. It can't be in a magical device because any spell that makes a permanent thing must be a ritual regardless of the level. A spell that temporarily changes a creature into another creature doesn't have the ritual requirement.
This isn't (at least to my reading of it) a new restriction in Hermetic Projects, it's just restating the rules from the core book.
Reading the example spell in Hermetic projects, I see that it creates a might 20 wolf and a might 50 dragon at the base level to create a magical creature, no additional cost for might.
That isn't clear to me - can you expand on your reasoning? Yes, if you're going to do it via ritual makes sense to do it as a momentary spell, but that's not the same as "it's only a ritual because you're trying to do it instantaneously".
For reference, the bit I'm particularly focussing on is the section at the top of the third column ("A spell that creates a magic animal is always a ritual, and cannot be instilled in an enchanted device") - I agree the earlier wording in the second column is slightly more ambiguous.
It's that first and second column that drove me to my conclusion:
The title of the section is creating magical creatures.
As I read it again I see it's not quite as clear as I originally thought. Certainly a wand that spits out duration sun might 50 phoenixes with unlimited uses per day might worth restricting.
Yet even if it was a new restriction, rather than an explanation of what was in the core book it wouldn't necessarily be worth transferring to a muto spell in the familiar bond. I have a difficult time classifying a rule that says a magus cant turn their owl familiar into a fire breathing dragon as anything but a fun killer.
Seeing the weirdness of applying the Creo Animal guidelines which provide no accommodation for might, I think it would make more sense to go with the adapting the animae magic guidelines from mystery cults page 94.
So base 10 change an animal into an elemental, one additional might per level, not sure if I should do something different with a magical animal, I'm thinking not.
Does that seem too easy, like our character is gainng the benfits of amystery virtue without having any such virtue?
Erik, there's a thing on the ratio of Size to Might to Level of Spell of Elementals in the Magical Things section of RoP:M - upper box of page 133 is one reference.
How to get or give general MR by a spell is one of the big mysteries that so far has eluded the Order of Hermes. See e. g. ArM5 p.161 box Rego Vim Guidelines.
Just Muto-ing oneself or something else into a being with Might (hence MR) and then keeping this form is begging to have the SG invoke those problems involved with long term Muto effects described e. g. in ArM5 p.132 box Muto Corpus Guidelines and referenced in ArM5 p.118 box Muto Animal Guidelines.
Theorizing on that topic without a troupe and SG can indeed show nicely the complexity of Ars Magica 5 rules, though.
I was going to bring up the same point. It doesn't solidly lock things in here, but it does shape my opinion a lot.
Based on this, I would not think MuCo or MuCo(Vi) to change yourself into some sort of Magic Kin or Transformed Human would work, as you could essentially leave yourself as you are while adding Magic Resistance. If not with MuCo, then I wouldn't allow it with MuCo(An) nor with MuAn. Also, I think allowing this steps on the toes of things like Animae Magic, whose magic requires a Major Virtue to change the caster's magic to accomplish similar.
that was really my impetus for starting the thread. If magi can create creatures with might, can they turn things in to creatures with might? Is there a good way to both respect the difficulty of breaking what Hedge magic revised calls the minor limit of magic resistance without pooping all over the obviously fun idea of changing the form of one's familiar into a different magical beast?
That was me misreading your "one magnitude for 10 Might."
But I think the 'misreading' makes more sense. One magnitude of spell is one magnitude of Might is one pawn of vis. So PeVi to destroy a magical critter is one level per point of Might; it's the same to create (once you have your baseline, to reflect that destruction is easy for Hermetic Magic.)
Except for being able to sustain the thing indefinitely without Warping.
You can absolutely turn your owl familiar into a fire breathing dragon (assuming you can manage the relevant lab totals) - or indeed turn a mundane animal into one. "Give a animal a "magical" ability such as the ability to breathe fire (requires a requisite for the ability)" is one of the standard guidelines in the main book, as is "turn an animal into a different animal".
What I don't think you can do is give it (more) might in the process.
Typically a familiar gains Might by consuming lots of vis for (RoP:M p.52) Transformation, thereby repeatedly getting instances of (RoP:M p.41) Improved Might. The magus just needs to provide time, vis and motivation: the familiar does the rest.
Changing the shape of a familiar is typically done with ArM5 p.105 Shapechanging effects invested into the familiar bond.
Do you still miss any fun that you mentioned in the OP?