Muto - Targetting in relation to essential nature and cancelling spells

We have a magus in our party who is size +2. He's got a spell that let's him change his size by +1 or -1. The default version of the spell only targets a max of size +1, so to affect himself, he did need to make a variant of the spell that's 1 magnitude higher.

My question is, once he's mutated to size +3, can he use the spell to shrink himself back to size +2, or even to size +1?

One interpretation is his essential nature is size +2, so he's targetable. The other interpretation is he's size +3, the spell can only target size +2, so it doesn't work. Obviously an answer is, go up 1 more magnitude, however, just out of gauntlet, adding 10 levels to a spell is not trivial.

Assuming he can't target himself due to being size +3, (which reading the forums seems to be right, but I couldn't find any answer that convinced me 100%) as a different solution to the issue, can he cancel the spell that's on him. I have read the rule book searching for spell cancellation and can't see it? I just sort of assumed one could turn off a non ritual duration spell that you've cast. Is that right?

I was thinking as a safety, my mage would cast wizards sidestep each morning. If he's dealing with mundanes, and goes to shake a hand or sit on a chair, etc, it would look very wrong and disconcerting. If I can't cancel the spell, I may have to rethink that strategy.

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I would allow the spell to be used to return back to normal. I would not penalize the player, or his character, in this way. I would do this no matter what the 'official' rules say about it as for me fun is more important.

All that said, very nifty question, and I am interested in seeing what others think about it as well.

Also, and this is very important, hello, and welcome to the forums! :slight_smile:

I think you hit the nail pretty much on the head with your two different options for how to interpret whether or not your character can cast the spell on himself the second time.

I am personally inclined to say that he cant, but I cannot rightly tell you that my interpretation is better than anyone else's.

Cancelling your own spells is kind of in the core book. Namely its a virtue called "Harnessed Magic" listed on page 43 of the Core Rulebook. This virtue however comes with a pretty serious drawback if you want to leave a magical legacy. Given that the ability to cancel your own spells is specifically a virtue I would say that it is not something you can do without this virtue.

Your other option is use Vim spells to circumvent this problem. I can think of a number of options available to you here, but the most simple is probably to learn some PeVi spell that dispels the MuCo spell.

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There was a related discussion last autumn on this forum.

We have for this (ArM5 p.132 box Muto Corpus Guidelines): "Certain shapechanging spells allow the target to change back by concentrating. While concentrating, you symbolically remove some item to break the spell, such as a wolfskin cloak or some water in your hands. These foci are essential if you are to be able to break the spell in this way. If you cast the spell without them, you must either dispel the magic with Perdo Vim, or wait for the duration to expire."

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Adding 1 magnitude for size allows you to affect 10 times the mass, which is a change of 3 levels of size. By adding a single magnitude for size, your player could affect a (Corpus) target up size +3.
No, it's not very clearly written, you have to combine the information in the box on page 113 of the core book, with the information about size on page 192, also in the core book.

Since the spell was redesigned, did your player remember to change range to Personal?

Base corpus is up ti +1 size. So with a magnitude added it should be up to +4 size, not +3.

My apologies, I was trying to say "+1 magnitude is +3 size modifier, ie going from Size +1 to Size +4 for Corpus (or eg Animal)."

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For an example, I would suggest Assume the Stature of the Giants of Eld from Magi of Hermes, p. 49.
Now, I cannot recommend that particular tome for examples in the general case, but this particular effect appears to be correct.

Thanks for the answers so far.

I'm thinking my preferred option would be for all other techniques, except Muto, it's all about the size and shape. What's the point of turning an elephant in to a mouse, if the mouse remains difficult to lift, burn, etc? It seems thematically bad to be able to break the leg of the essential human inside, when they've been transformed to a fish.

For Muto though, I think the essential form is a better way to go. It means the character's concept works (which is a big selling point for me) and I really like the essential nature concept, so giving it a bit more prominence appeals to me.

It will be interesting to see my Story Guides opinion.

The side conversation on cancelling spells that have sun duration has interesting consequences. A magus could put some effort in to getting good penetration against themselves to cancel their own spells, however, they'd need to put some focus on Perdo Vim, as it's not just getting through their own Parma, it's having the grunt to cancel the spell. Or I could try to convince the SG we should be able to cancel our own non ritual duration spells as a house rule if we set up some kind of connection as One Shot mentioned about the Muto spells.......

In my opinion, his Essential Nature prevents multiple castings of the spell from stacking - in other words if he starts as Size +2, then this spell can only change his size between Size +1 and Size +3, no matter how many times it is cast.
So if he casts the spell once to reduce his size to +1, then casting aagin can only make him Size +2, not Size +0. (The spells effect is only one size level per casting, no?).

Normally I would say a magic spell designed to be capped at Size +2 would not affect a Size +3 character, as he is currently just too big to be affected. However, if it is a personal range spell...

Perhaps I should default to other Muto spells, like change person into an animal. Would casting the same spell a second time change the animal back into a person?

I am having difficulty tracking down a reference in the Ars 5 books.
I seem to recall there is something written somewhere along the lines that when a human is transformed into an animal, Corpus spells can still be successfully cast upon them. The exception being Bjornaer Magi, whose Heartbeast ability is outside of Hermetic Magic.

But where?
If this is a valid reference, why would transformed Size be different to transformed Form?

HoH:MC Bjornaer section Ringing the Changes box on page 22.

Thanks. Somehow I missed that on the first pass.