I'm torn on a small spell design issue, more specifically, its classification.
The spell is "The curse of Babel."
The spell causes the target to spout gibberish whenever he speaks. He can still understand and read the languages he knows, but when he tries to speak words or write them down, they appear as gibberish.
I'm not sure wether to make this a Perdo Corpus spell (hampering a person's ability to read and write, as he can still understand the written form, and what is spoken to him), or to make it a Muto Mentem spell (The twisting of the mind's ability to express thoughts and understanding).
I would appreciate any suggestions. Thanks in advance.
This may just make it worse, but there's another option:
The Rego Corpus guideline that makes body parts fail to respond properly and such could, arguably, be used here.
Then again, they may all be valid. There's more than one way to do a lot of things in Ars Magica. I don't remember where I saw it before, but someone used the example of different ways to get ice. Creo Aquam to create ice, Rego Aquam to freeze water, Perdo Ignem to freeze water, Muto Aquam to change something into ice, or hey, Creo Imaginem and you can at least pretend there's ice.
Muto Imaginem would be more appropriate in my eyes, twisting the words as he speaks them. Of your two choices, I'd go with Mentem, but can't decide between Perdo and Muto. Languages are something in the mind.
what are your strong arts? Use them. If..
PeCo, then destroy his tounge
PeMe, destroy his speaking knowledge
ReCo, twist his tounge
ReMe, Make him think he cant speak
MuCo, change his tounge
MuIm, change what he says
PeIm, destroy what he says (will appear mute)
CrIm, create more voices so he appears to speakmultiple things/voicesat once
MuMe, change what he knows as language
CrMe, creatememories of a languge of gibberish.
Obviously some of these will work better than others, and somewill have side effects, but just go with what your best at.