I think I want to create a mute magus. Other disabilities quickly lead to debates about scrying, but being unable to speak won't.
So this is what I have so far
Mute - flaw
quiet magic (2x)
Now obviously Im magic is useful to communicate anyway. So is Me magic. But I'm not sure about how a parma works in this case? Would it stop an artificially created voice? Can a mute magus create a voice using magic at all? Or would he have to rely on projecting pictures into the mind of the other person or on creating "silent movies"? Is there any minor magical focus useful in this situation? Could he "fake" speaking?
If you use creo imaginem for me the parma magica don't stop the species.
If you use creo mentem to create word in the head the parma magica will stop this. You can overcome this with a minor magical focus and a high score in penetration.
but it could be considered as an attack.
You can use a creo ignem to create light with a complement rego. The parma will no stop the spell.
Or you can use a spell muto imaginem for translate the movements of your hands in sound.
+1 for the whole "parma doesn't stop creo Imaginam" thing. I believe the theory is that the species are (naturally) created as a consequence of the (magically-created) image. Similarly, parma doesn't stop a magus getting (naturally) wetted from a (magical) raincloud - as rain is a natural consequence of a cloud.
On a side note, you can create completely normal (and permanent) fertilizer from magical cows and magical horses.
I remember reading of a mute historic noble wrote on wax tablets but also had a gesture language he used with family and a few trusted servants. There is a good chance your mage might have a personal language and might have acquired a valet who also knows it. while this would not be a complex language it would be an interesting point to have private communications without magic right under other mages noses.