Well, as the spell is a Creo spell, the target is what is made, not where it is made at. The term target in the way it is used in spell design in 5th edition is a bit confusing.
It could be the essential nature of man to cowl before the Gifted.
I don't see anything wrong with it from a design standpoint (I am a bit low on experience).
However, any magus casting that on a person is going to have to be aware of how it will look to others. A sudden dramatic loss of ability to figure out which way was which? It would probably be assumed to be possession of some sort. If the magus uses it regularly, it will practically be a sign-post pointing back to one source. While mundanes would not necessarily be able to follow the directions, the Quaesitoris could.
I'll be copying that for myself. 
Ok, I see the sidebar for that.
I need more practice with this.
My question is, do you think it is possible to design a formulaic spell at a higher level than needed for the effect chosen in order to obtain a fixed amount of built-in spell penetration for the spell?
No.
Why?
Because of the very way RAW defines penetration. ArM5 p82
Here's what could happen if this were allowed. Suppose Alice can cast Pilum of Confetti, a level 20 spell. Bob designs his own version of Pilum of Confetti: a level 30 spell that is identical except that it has a +10 Penetration bonus built in. If Alice casts her spell with a casting total of 20, then the spell goes off but her Penetration score is 0. If Bob casts his spell with a casting total of 20, then he loses a Fatigue level, but the spell goes off with a Penetration of 10. In other words, Bob is getting extra Penetration essentially for free. If this prospect doesn't bother your troupe, then by all means design a spell that works that way.
On an analogous note, I favor letting magi using craft magic add magnitudes to a spell to increase their Finesse score (another non-RAW prospect). But it's been pointed out to me that if one could do this to increase the Finesse scores of combat spells, it would get around the need to overcome Magic Resistance. So as with all house rules, one needs to make sure that it doesn't open up some different, unintended use that is undesired.
Except it wasn't free. Bob had to invent a spell two magnitudes higher. It's a more powerful spell, so of course it does more. Also, he lost a fatigue level casting the spell when his opponent did not.
If you want extra penetration, Master the spell and use spell foci (Potent magic, as they call it now). Penetration is not a feature of normal casting. I would be wary to introduce it as a normal feature of a spell. Precisely because of that: he achieved penetration even if he had to fatigue himself. I do not like that. Life linked sponts could achieve something similar if you want.
Cheers,
Xavi
I don't see anything in that section that suggests designing spell penetration info formulaic spells isn't possible. If you do, I apologize that I will need you to explain in detail what it is.
Directly above the rules on spell penetration, it discusses how it is possible to add extra spell penetration into spontaneous spell casting. Also, it is possible to design enchanted devices with extra penetration (ArM5 p. 99). The existing RAW, to me, points directly toward the possibility of designing formulaic spells with extra spell penetration.
I apologize but I thought Penetration was a part of every spell casting operation. I guess you can avoid worrying about it for targets with no magic resistance, but I thought penetration was still "technically" there.
That is why I am here asking questions.
Penetration is supposed to be what extra energy you have remaining after fully powering our spell. Or something along these lines. An extra push you give to the spell once it is well on its way. Having a +10 (or +40, since nothing stops you at this level!) penetration when you have problems casting the spell sounds weird to me. it is like that Pirelli advertisement: "power without control is worthless". To me here this is what is happening: you are giving extra potence to your spell without a proper steering gear. The result should be a crash, not better success. YMMV 
Mastering the spell, using potent magic or investing in vis to boost your casting total AND push it is the way to go, I would say
Cheers,
Xavi
"Penetration total = Casting total + Penetration bonus - spell level", hard to miss.
Not really. When sponting, you choose the spell level after casting it. You could say: "Oh geez, I don't have enough penetration for a medium wound! Light wound it is then!" but that's because you are changing the spell level, not reserving penetration.
LLSM on p44 is the closest to what you are thinking on spont, but once again it does not directly affect penetration, but causes fatigue and wounds to get a minimum casting total.
Enchanted device with Penetration have a higher casting total than the required spell level, that's it and nothing more.
If you pick any other interpretation, you directly contradicts the formula above.
As others have said, because it's not the way that the rules work.
It also doesn't really do anything.
Say I have a level 10 spell to cast (and under your variant a level 20 spell which is the same, but which has +10 penetration "built-in").
So, now out in the field I generate a Casting Score of 30 (and assume I have no Penetration Ability). The Penetration of the level 10 spell is 30 - 10 = 20. The Penetration of the level 20 variant is 30 - 20 = 10 + 10 = 20. So, nothing is achieved, except that it was more difficult to invent the level 20 spell.
Alternatively, if out in the field I generate a Casting Score of 10. The Penetration of the level 10 spell is 10 - 10 = 0. And the level 20 variant spell takes effect (as the Casting Total is within 10 of the spell level). The Penetration of the level 20 spell is 10 - 20 = -10 + 10 = 0. So, again nothing achieved, except that for the level 20 spell it was more difficult to invent and you lost a Fatigue during Casting.
It is possible for a character to increase his Penetration for a particular spell, that is what the Penetration spell Mastery is for, and it is one reason why you might want to spend vis during spell casting, and, of course, your character has a Penetration Ability and the possibility of collecting Arcane Connections.
I see nothing in that formula that states, "You cannot design a forumulaic spell with additional penetration."
If a formulaic spell had additional penetration designed into it, then it would be a part of the "Penetration" value in the formula.
Thank you. I hadn't worked that part out.
Sure it does.
If you´re expected casting roll is between 10 and 19, the level 20 with 10 built in penetration is better.
You trade fatigue for a guaranteed amount of penetration.
Another question about spell design.
The question is this: I added Base 30 "Kill a person" to 5 "Destroy a corpse" to get the total Base 35. Was that addition correct, and if not, what would have been right (if anything)?