Greetings everyone. I am new to the forums, but hope to become an active member. My first few posts involve questions I have on some of the spell guidelines / designs based on the new ArM5e rules.

For starters...

Eyes of the Cat
MuCo 5 (Re: An)
(Touch, Sun, Individual)
(Base 2, +1 Touch, +2 Sun, free requisite)

My question is, as this spell only affects the eyes of the target, by literally changing them into those of a cat, should it not have a target of Part, and thus be Level 10?

The distinction between the Targets of Individual and Part seem clear enough upon reading them, but they become less clear upon looking at specific spells.

Thanks,

Nzld

Yes, you could look at it that way. I think the guideline that was applied was "Change someone to give a minor ability" - the minor ability in this case is the ability to see in the dark. This is actually easier than changing the person's eyes. I think the real effect of the spell is consistent with a Level 5 spell of Target: Individual, and the fact that it changes a person's eyes is just window dressing so it did not affect the level.

Sometimes, you will find that you can apply the spell guidelines two different ways and get two different levels for the effect. This does not happen very often but it can occur. When it does, I just shrug and take the lower level effect. The spell guidelines have been well thought-out and tested but they are not 100% bulletproof - there are a few logical inconsistencies.

I believe the way Eyes of the Cat works is by changing a person's eyes to affect how they work. This is different than a magical sense spell in my opinion because a magical sense spell would allow the subject to percieve things that were completely imperceptible before. Also, a magical sense spell would allow one to sense only items of one Form - Intellego Corpus with T: Vision would let one sense people (even in complete darkness, or if you were blindfolded) but not walls or trees.

This is just my interpretation of the difference because you asked what people think.

The Muto spell guidelines do allow one to cast spells that grant minor abilities. For example, one could cast a spell that makes a person more buoyant so he can swim while wearing armor. Eyes of the Cat to me is a similar principle, it makes a person better able to see in the dark.

Also I think it's true that with a magic system as general and flexible as Ars Magica, there can be more than one way to get the same effect. I can think of three ways to make an invisibility spell: Perdo Imaginem to destroy the species, Rego Ignem to stop light traveling away from the subject and carrying species with it, or Rego Mentem to stop people from noticing the "invisible" subject. Not all of these would be the same level - Perdo Imaginem should be easiest because it's the most simple - but there is more than one way to skin a cat. A magus might want to use Mentem-based "invisibility" if he were very strong in Mentem and weak in Imaginem, for example.

So I do think one could create a magical-sense spell to let one see in the dark, but it would likely be higher level than Eyes of the Cat.

I don't think that Mu Co spells to change a person's eyes invalidate Int spells with target vision

here are example effects (off the top of my head) that I can't see how you'd do with Mu Co

Int An you could see the agresive thoughts within any animal

Int Aq see through water as easily as air. (OK if you were under water I supose that you could MuCo yourself some fish eyes). But you could see how fresh or foul water is.

Int Au see the winds and thereby target your arrows better. See through fog as if it were clear.

Int Co see disease, see through disguises

Int He see the health of plants see their poisonis or healthful properties.

Int Ig see how hot or cold thigs are, see beyond blinding lights

Int Im see in complete darkness, see through illusions

Int Me see violent or harmful thoughts

Int Te see mineral deposits through the overlying dirt, see through walls

Int Vi See regio borders, see magic resistance

// I don't think that Mu Co spells to change a person's eyes invalidate Int spells with target vision

Neither do I! What makes you even mention that - nothing in my post was meant to say there is anything invalid about In spells with Target: Vision. It seems there has been a misunderstanding here.

I'd say that you should have the spell level at 10, with the target as "part", as the eyes are part of the body (not unlike Arm of the Infant targeting a different part of the body). I agree with the rest of what you had in the spell, including the requisite.

I'm sure there's another way to do it with Im spells affecting the senses, and other mages might have done it that way - there might have been someone really good with Imaginem who had a deficiency with Animal or Corpus who couldn't do the spell the one way so developed it as an InIm spell. That would also be a way to do "Eyes of the Bat"