I have a player who has come up with an interesting idea I thought I might share and see what you guys think. He wants to change either shadow or fire and make it into a 'gem' using muto magic.
So, for example lets take the shadow - he's a Merinita magus, so he has access to some interesting durations for his spells - so we can have something like this:
Spell - A Dark Gem
MuIm10 (base 2 - affect 2 sensations, Range:Touch, Duration: Bargain, Target: Circle)
The spell gathers the shadows cast by the fire and draws them together, giving them both the shape of a cut gem and making the shadow solid and feel like stone - the things the shadows are drawn from will not cast shadows from the fire in question until the effect ends
After creating this he then wants to enchant the resulting shadow gem - from what I can see in the rules this can be created, and so long as the fire is maintained the gem will remain so he could, with enough care, do this.
From one point of view its a risky thing to do since your enchanted item can be destroyed with a bucket of water - but thematically its pretty cool (and I'm guessing the form bonuses for it should be quite cool as well) but my question would be how would you guys deal with this and how many pawns of vis could something like this hold, if it can be enchanted at all?
I think he's going to have requisites for the form of the item he's turning the shadows into. In this case, Terram. See, for example, the level 25 MuMe guideline to turn thoughts into an object, and the spell Inmost Companion. You also might have a +2 magnitude for changing something into a gemstone, as per the MuTe guidelines.
All of this would make the spell significantly harder to cast, but I don't necessarily see that as a bad thing, since my impression is you want the resulting shadowy gemstone to be quite useful. So the spell should not be easy.
my understanding of Muto is that you can change the properties of a thing, so you could have actual solid shadow in the shape of a gem, without it actually having to turn it into stone or something else?
If he turned it into a stone of some description then that would answer the question of how much vis it could hold I suppose though.
One crucial observation is that in ArM5 shadows are not something, they are the lack of something (light). So you can't manipulate them directly any more than you can manipulate directly a hole in the ground (and e.g. turn it into a badger).
The core book states that shadows can be manipulated by Imaginem (p143) however on Perdo Imaginem guidelines it then goes on to say that they are manipulated with Ignem instead...
What the core book states is: "Stenches and perfumes, tints and stains, color and shadow, melody and cacophony, sweet and sour; all these are perceptions, and so can be manipulated by the Art of Imaginem." I read it as saying that you can change how dark or red or shiny an object looks with Imaginem. But you are affecting the image of the object, you are not affecting the "shadow" itself, or the "colour red" itself. You can't transform a shadow into a gemstone, any more than you can transform the red colour of a ruby into a badger -- netting you a colourless ruby and a badger.
So he can enchant it. He wants to make it into something he can enchant and turn into an interesting talisman. A gem is just an example, he has mainly been talking about turning shadow into a cloth like substance he can turn into a cloak.
My reading of the rules is similar to silveroak's (though I feel I need to read some Aristotle for more info on what shadows are in Ars), in that he could do it - the main question I have is could such a thing be enchanted and assuming it can be what would you say the base vis capacity of it would be?
Could Ritual Cr(Fo) + requisites (Im or Ig) + the extra magnitudes for unnatural properties listed in the guideline boxes work?
An indirect approach? Ritual CrAn(Vi, Fo) to create a magic animal that does what you need? Say a magical shadow lynx whose urine hardens into a shadow gem?
Cool idea - I know creo magic can't be used to make something unless the caster has knowledge of that real thing - but that could be the basis for an adventure - so an excellent idea!