One player is in the process of creating a master of illusions and the topic of formulaic CrIm spells came up, as one might expect it would. We have not been able to come up with any sort of agreement about how such spells work, so off to the forums I went.
Poking around I found the thread,Reforming Spell Guidelines for ArM6?, which has a discussion of formulaic illusion spells. My take away from that topic is "troupe's discretion" since the rules seem a little vague on the matter. My current thinking is that extra magnitudes result in much more flexible spells and for highly specific spells a 1 magnitude reduction is in order. And fine tuning the effect of the spell (e.g. the colour of the shirt) is a finesse roll. The issue is, of course, what's the baseline.
If you would indulge me, some feedback from more experienced Ars Magica practitioners on the following spell concepts would be appreciated. Note that all these spells can be cast spontaneously; I am using them merely as a point of discussion.
A spell to create an illusion of a bodyguard -- Can the same spell create 2 bodyguards? 3? Instead of appearing to guard someone, could the spell be used to create the illusion of someone playing chess?
A spell that shows two people walking -- can the same spell show two lovers walking hand in hand or two guards walking and appearing observant or a rich person and his/her spouse out for a stroll? How about two people running away?
A spell to create a cat -- could this spell also create a dog or pig or mink? What about a bird? Or a toad?
A spell to create the sound of footsteps - Can the spell create the sound of footsteps on any surface (stone, wood, snow)? Can the spell make the footsteps sound like they are approaching or receding? Can the spell make the sound of variable number of footsteps or just a specific number?
A spell to create clothing - Can it create anything from hosiery to a doublet?