Strength of Hercules
MuCo25
The magus investigated a particular person (Günther) and used some of his physical attributes as a base to this spell.
The spell changes a persons size to +2, his strength to +5 and stamina to +3.
Suitable requisites needed if clothing and armaments should change, too.
Following the analogy of the rulebook you may need to place Günther's skin over the target person.
Base 5 (a tip), touch, sun, part.
Wasn't there a MuCo spell in the ArM rulebook to change size and its effects? I thought so, but I have never been much into Corpus really, except in Rego & health spells, so Serf's parma ATM.
The spell sounds about right to me.
Cheers,
Xavi
This seems quite overpowered, but first things first.
Why the T:Part? Secondly such a spell would be calculated and added to the target's existing size and characteristics rather than give a fixed result, or if giving a fixed result needs to be very high so that even targets with zero, or less, strenght and Stamina also ends up with these characteristics, and finally I've been unable to find any base level for changing size but 3 for changing one level upward in size and needs to be convinced how you decide interpret a change of 2 or 3 upward in size.
This is certainly doable but at the moment I seems too low a level.
Reason of the Part target is because of the magus wants only get some elements of Günther's body and not to change the target to Günther. For example the target's face shouldn't be altered. Only his size, strength and stamina.
MuCo analogies suggest there is no problem to change the size into a determined number. See any spell, e.g. Cloak of Black Feathers. It chages into a raven but there is no level change however the size of a human and a raven is obviously different.
Changing size is level 3 and I raised this simply to 5. I didn't bothered with size modifiers and such.
What stats will the character have as an animal? I didn't find any rules. This would help a bit in this question, too.
The guy is not changing into gunter as described: he is simply becoming larger and getting some nice hefty bonuses due to that. The target should be Individual. UI hadn't noticed that before.
In general, ther eare guidelines (IIRC in a spell) that give you the changes in attack, defence, strength and stamina associated with a change in size.
Cheers,
Xavi
After reading mundane beasts I think the magus can lend the physical abilities even from a bear. In this case the strength will be +6 and the stamina +4. What about lending the strength of a dragon?
I could agree to reduce the target into individual. It's cheaper. 
This is only a technical question.
Ok, so changing the size of a person is base 3, but you're adding stamina and strength as well... so I'd go with the base of 10, for shifting into a land animal since you essentially want to give him the bear traits.
The target is individual, because you're changing the majority of the individual, range is touch, as you wanted, duration is sun, as wanted...
Now to keep the person's hands normal and allow them human speech, I'd include a magnitude, to maintain that aspect. It's certainly not cosmetic as we're talking about obviating silent and still casting penalties and continuing to wield weapons. Maintaining a human appearance, that I'd call cosmetic. If you wanted it for a fully armed grog, and wanted it to shift his weapons as well, there'd be a terram requisite. Again, that wouldn't be cosmetic, because we're talking about all the benefits of armor...
10(base for transforming into a land animal)+1(touch)+2(sun)+1(add'l effect)+1(Te)-> MuCo35
MuCo 35 Shroud of Ursus Martial
Laying a bearskin over the target and casting this spell, the recipient becomes Size +2, shifts strength to +6 and stamina to +4 (This may be a penalty in some extreme cases.), gains +2 soak, and otherwise maintains his human appearance and capabilities. Armor, if any, shifts with the target in size. The bearskin becomes a cloak worn by the now obviously unnaturally large person. The spell can be ended at any time by removing the bearskin.
You could regain a magnitude by dropping the terram requisite, but then you'd need to have his new, larger gear handy. It's arguable that the recipient should get the bear's soak... as you're basically going to sidestep what would be 6(!) magnitudes necessary just to provide someone with another +6 soak by turning them into a bear and then adding one magnitude to keep some human traits. I'd leave it as is, maybe even drop the +2 soak from it, depending on how a playtest showed it to work.
-Ben.
HI all,
I m really interested in this "concept".
But if I well understand, you can "transform" a human into an other human for a duration of Sun with a 5 to 7 magnitude spell. The ize will increase as well as strengh (+5) and Sta (+3)
So if I cast this spell on a standard peon (1 strengh 1 stamina) , he will get +4 in strengh and +2 in stamina.
But if I cast a creo corpus spell to increase at sun its strengh from 1 to 2, the level is 35+5(touch)+10(sun) = 50 ... so close to the limit for ritual.
Is that no too powerfull then for a simple MuCo spell ?
For me, the way I understand the MuCoAn transforming a human into a bear is that the human acquires the shape and the standard str and sta score of a bear, no more.
So for me, such a Muto Corpus should give standard Human score (therefore 0).
What do you think ?
I think that the key for muto is that "By using muto magic a magus can grant or remove properties that an object cannot naturally have" (p.78) So giving the target a +6 score or more would be within the realm of muto.
I don't see a problem with Muto spells being much more efficient than creo spells in the adjustment of strength. The creo spell guidelines account for the permanent natural alteration of a score with a ritual spell at duration momentary (perhaps not the best design decision but it's what we have to work with). Muto spells can not be made permanent with rituals.
Leonis:
As I see your logic is changing the target into a bear and changing back some parts into his original form. This is overcomplicated. I used the part target to change only some parts and raise the level of the spell at the same time.
Terram req not needed to the base spell. Similar case when you use Leap of Homecoming with extra requisites to teleport even your items.
Joachim:
Yes I transmute the human into another human.
I don't think level 25 is low for this. You can easily lay out an opponent even with level 15 spells and became invisible with a level 15 spell.
At the bear idea I used the analogy of the Eye of the Cat. It lends an animal ability, seeing in the dark. The strenght, size and stamina are abilities of another animal. So maybe it needs the An requisite.
I get this bear idea only because there are no guidelines to increases with MuCo and wanted some background and explanation to the spell.
I think using wolf skin to changing into a wolf is only a remainder of the earlier editions. It is not coherent because to change persons into a pig doesn't need any material component. 
I'd agree with you about not needing the Te requisite (and we don't require it for LoH or 7LS either) except that the MuCo guidelines specifically state that to shift any accoutrements demands the requisite-- page 132, MuCo guidelines inset, top of the second column.
If you'd rather not use it, that's your choice. I'm just pointing out where I'm drawing my magnitude increases from within the rules.
As far as the baseline is concerned... I don't call Str+6, Sta+4, Size 2 a "minor" ability, equivalent to eyes of the cat. You're utterly changing the size (base 3), making it more resistant to damage (base 5) and giving them a "minor(?)" ability of increased strength (base 2).
To be honest, if it's like anything, it's like Preternatural Growth and Shrinking, but with the addition of more strength and stamina... so maybe the baseline of 10 isn't so off target--
Baseline 3 + 1 (str) + 1 (stam) + 1 (second size category) [baseline 10]+ 1 touch + 2 sun + 1 Te (to affect target arms/armor) -> MuCo 30... if you don't care about the arms and armor and plan on send the target out in a curtain and swinging a treestump, that works... and you can drop it to MuCo 25.
Both Shape of the Woodland Prowler and Cloak of Black Feathers use the "lay a cloak over the person" flavor fluff, and I like it; that's why I threw it in my example. Curse of Circe does not, you're right, but then she didn't do that in the stories, either.
-Ben.
And, on an average man, size, as Preternatural Growth and shrinking only gives + 1 to it.
And it is level 15...
... because it allows size reduction, too. Otherwise it would be level 10.