Spell Creation Help Needed

Just curious, where is that stated, on what page (approx)?

The little bar on page 79, says that Ice is basically Aquam (with ignem and terram forms) so if the spell above should have frozen mud, I would say that it would require more than just an ignem or Aquam requisite.
Thugh as an Elementalist, you would get 1 requisite for free, but the second requisite would add 1 magintude.

Then again, I have just read the book once and I have just started playing Ars Magica this last week. So I might be wrong.

But I would probably require that target was "Part" and not individual

It's the very first page of the Spells chapter, if I recall correctly, it's the Central Rule. Says something to the effect of, it may be possible for guidelines to create effects far more powerful than intended. Increase the level accordingly. There are a couple of ways to do this, but they require SG fiat or troupe consensus in both cases. First way is my method, increase it to ritual, which effectively moves it out of insta-kill in combat range. The other way is to just rule that particular effect is a higher guideline.

T:Part isn't allowed for Creo spells, Group and Individual only. Keep in mind, there's a difference between targets and Targets. This CrTe is creating a piece of stone as its Target inside the mouth of of the small "t" target, or recipient of the spell.

Thinking some more about the spell, I'm not sure you can put the stone into the heart at this level, I'm trying to figure this out given the guidelines, and I am not quite there, yet. Might just rule that it becomes a Corpus spell, and thus uses the significantly higher guideline outlined above. It's not a Creo Terram spell to affect the inside of the body (I know the mouth is inside, but we can all see it is diferent to create something that impedes speech, or something that kills instantly), but instead Corpus spell with requisites. Or something.

For what it's worth, I won't allow one object to be created inside another a living creature (I had though there was a formal rule, but I can't locate any at the moment. In any case, my reasoning was that:

  1. Two objects cannot occupy the same point in space. Therefore, such a spell is impossible under Bonisagus, theory.
  2. You cannot (usually) perceive a target's innards. Therefore, they cannot be targeted.
  3. Such a spell causes physical harm to its target. Therefore, it cannot be accomplished via Creo.

By any of my guidelines, however, creating a pebble in the target's mouth would constitute a gray area.

I agree with these thesis and I reason in the same way. So thus, I will not allow it, should I ever be a Story Guide. However a Muto Corpus (with Terram Requisite) should be allowed to turn someone's tongue to stone. But only if you can see your target's tongue (as if if the target was already speaking or having the mouth wide open when you cast your spell (Though this would require a target roll to time the spell while the mouth is open).

I'm having trouble with T:Part being perceived. I think there are some spells that can affect T:Part as long as the entire Individual it is part of can be sensed. I can't find any examples of this, but such a restriction might make some canonical spells impossible.
The description of T: Part even mentions the human heart as a valid part, and a magus from a long ways away, without augmented senses cannot sense the individual's heart directly.

Entilzha, keep in mind that a spell to change the tongue to stone is in the 35-50th level range, depending on Range and duration. It's already hard enough to do it without requiring seeing the tongue.

As a SG, I agree with this and I will not, just as Gremlin44 wrote, allow an object to be created within another living creature.