Ok, this isn't directly related to the rules or the gameplay of Ars Magica, but I'm curious nontheless. I know that Imago is the latin word for image, but why is it Imaginem in Ars Magica? How is that word built up? Can someone with better knowledge of Latin that me break it down for me? 
E.
Thanks. Didn't understand too much of that, but I think I see the point
E.
See, that's why latin words are listed with nominative (imago), genitive (imaginis) and gender. Here, the imag- stem of the nominative case becomes imagin- in other cases. "Imparisyllabic" means just that: it acquires another syllable. Look at homo, hominis, it's built on the same model.
Why did 'o' become 'in'? I don't know. I'm sure some latinist will come and tell us that there are precise rules as to when that happens (and what are the exceptions), but from my point of view (2 years of latin 15 years ago), it just falls into the "you need to know it's that way" category. Linguistic evolution and all that.
Ah, got it. Thanks.
E.