Which means # of pawns of Vis - mastery score +/- modifiers from flaws/virtues.
My post vanished so let's try again:
P86 under mastered spells: Mastered spells are always cast with a stress die but if the magus is relaxed, there are no botch dice even in a non-magic aura and using vis.
So a 0 would mean just a score of 0 since there are no botch dice (while a 1 still explodes). Since casting total though is only 37. Odds are that there would be 2-3 lt fatigue spent instead of just 1 so a couple extra days sleep after the spell.
Every pawn of vis used in spellcasting adds a botch die, so unless your mastery score is equal to or greater than the magnitude of a ritual, there will still be botch dice.
Except in this specific case of a mastered spell cast when mage is relaxed.
Normally vis adds to botch dice, this specific situation under mastery is explicit exception where it says there are NO BOTCH DICE even if foreign aura or using vis.
I'd say casting a ritual is never relaxed. That's me, though. RAW certainly seems to imply someone with a Mastery of 1 never rolls botch dice if relaxed. I just can't envision handling 9 pawns of vis and not being nervous...
So, when was the Hercules spell learned/invented? I can't seem to see when he invented the spell.
Secondly, technically, according to the chargen rules, the amount of vis available for use annually is 5xMT, which in this case is a max of 25 (assuming puissant counts). Unless the remainder of vis is coming from the 75 bps, then that's problematic unless it is spread over multiple years.
I tend to agree with The Fixer's comments about these being Mercere Secrets, but it's possible that some of these have leaked out over time and people might find a lab text or trade for one. Kinda wonder how a Tytalus convinced a Magical Mercere to give up secrets of the House.
The RAW also implies that Ritual Magic is never relaxed-- "The magnitude of Ritual spells, and the need to incorporate many elements, mean that they are always cast using a stress die." (p. 81) But the section on Mastered spells doesn't specify whether they are explicitly including ritual spells, or if by "...when using vis" they are referring to vis boosting of non-ritual spells, or all uses of vis, so it IS ambiguous.
The character got the ritual during his apprenticeship, so he never invented it. The vis is from bp.
This could be abusive:
it grants the equivalent of 4x improved characteristics at the cost of just 54p of vis, 45lvls of spells (+ the high CrCo lab total to cast it), and 5xp of mastery.
Worse: Another character could use this on a stat that is more relevant than Strength (which the character only uses for wearing armor when expecting combat)
So - peregrine: ban it.
I'll change a few starting spells for another concept of defense. Based on ReCo and Auram spells.
I disagree about these being mercere secrets. They are guidelines in the main book long before HoH:TL came out about Mercere having and using the spells. I would say they are not common spells and ones that are shared but any wizard can invent them for him or herself and potentially pass them to apprentices. I suspect they are in the library at Durenmar.
Of course they are spells that you have to be very good to invent and cast and you have to get the vis for it. This is though the sort of thing which lets arch mages be arch mages and better than younger mages.
I would be fine if this spell were invented from first principles, it was not. It was part of the character at apprenticeship, and therefore it was learned from lab text, or taught to him by his pater. Not sure why a Tytalus pater would share the knowledge so willingly to an apprentice.
There is that: I could easily see it for a bonisagus, mercere or Tremere. Even a Bjornaer. Jerbiton would teach the mental ones potentially. Tytalus would make it challenge for apprentice to teach themselves and make it for themselves. Same for criamon as part of enigma and self development.
Not sure what Merinita would do. Ex Misc would be a hit or miss on this sort of thing. More likely yes since they need every advantage versus the other traditional houses. Queasitors are more likely the mental ones but who knows.
Still it is possible for any specific mater/pater to teach their apprentice or make the labtext available to a challenge to see if it could be learned.
Well, this is a philosphical discussion, which is appropriate to the House of Tytalus. I see a master going two different ways, "if it is so important, invent it yourself, boy." Or, the other way, "Sure, take it and learn it" and the master is killing him with kindness. Maybe by giving him everything, he's given him nothing. Sure, he's strong, what does that mean in the context of the battle between Physis and Nomos? Could it be that the Master doesn't respect the student, that he gave this spell as a lesson, thinking to himself about his filius: "of all the abilities you could've improved, you've chosen, arguably, the least important[1] to a magus, so please, take it." I can envision this being similar to a Tormenting Master flaw (which would balance out the increases in strength to some extent[2]). Maybe he's not tormenting, but maybe he's just really disappointed in his filius?
[1] Even for a martial magus, I find strength to be the least important of the physical skills, stamina possibly the most followed by quickness, with it's applications for fast cast defense and determining initiative order.
[2] Increasing strength from -3 to +3 is a six point swing worth Improved Characteristics x 4, so even attaching a full Tormenting Master flaw still leaves an essential virtue/flaw imbalance[3].
[3] None of this should be construed as a disapproval of the ability to act as a spell, but should be thought of as additional story possibilities. Ars magi can do almost anything. Should they do something, why they do it and what happens after they do it is where the most interesting parts of the story are.
I would look at it this way: You are weak, over there on the shelf is something that can fix it. Prove you can learn it. A challenge that is overcome when the spell is learned from the lab text. Benefit, person gets stronger.
Incentive to get very good in the arts. A challenge. I have no problem with JeanMichelle's character having it.
The more I think about it, the better I'm able to put my discomfort about the Hercules Ritual spell into words. To wit: it bothers me that a character is able to have, and cast, a spell at Character Creation that is able to do an end-around on the character creation process. Whether it's a spell or an enchanted item, you shouldn't be able to erase a negative characteristic (or even one that's lower than you'd like). Likewise, with a flaw: you shouldn't be able to have a spell/item that removes a Flaw.
And the fact that the one who invented the spell feels that it's open to abuse and should be banned tips the scales that much further.
So. No character may have, at creation, access to a spell that fundamentally and permanently alters the character design (for example, increasing their Characteristics, granting a Virtue, or removing a Flaw). Any such spells must be either invented during play or acquired via play, which will be difficult.
Learning it, or inventing it entirely by his own merits? Those are two different things when speaking in the context of Ars Magica. I have no problem with him inventing the spell, without the lab text. That would imply a CrCo lab total that is 91 or greater if he were to do it in a season, 78 or better to do it in two and 60 or better to do it in 3. Awesome. Specialized characters, to me, are much more fun to play, and to interact with. They have needs, and often work with other PCs to fulfill those needs, or SGs need to create NPCs to fill the gaps, again leads to richness of the story. IMO, A Tytalus master will never say there is something over on the shelf to fix it. He will instead say, "Yeah, you're weak, boy, what are you going to do about it?" It's the apprentice's problem, not the master's. If the master points to the lab text and says learn this, he's not a very effective Tytalus master. He hasn't challenged the apprentice to do what he must to solve his own problems.
Edit: seems that I had taken so long to reply that Peregrine posted about it and my comment is now moot. This can be deleted, or moved to Table Talk. I don't really wish to delete it, it's an interesting philosophical discussion, and as I have a Tytalus character brewing, my character and JM's may end up being competitive, or not. Who can tell with a Tytalus, and putting two together? Ha!
Hey, guys, may I point out that I wrote in my last post that I was going to remove the ritual.
Just one argument I found odd: A Tytalus master would never teach his apprentice such a useful spell. If that's true, then poor Malcolm Medicus.
I'll replace a few spells (I'll have to use non-corpus spells and give up my dream of a character just using one form 
):
The following looks a mess, but I plan to write it out clearly when I get to it.
So goodbye to:
- Leap of Homecoming ReCo35, Habeas Corpus CrCo30, Hermes Ritual CrCo45, Wizard's hop reCo20 (pg spell), Talisman (3 seasons), Str+3
Welcome to:
Attribute changes: Str-2, Pre +1, Dex -1
110 lvls of spells:
The Flying Doctor
ReCo25
R: Pers, D: Sun, T: Ind
The caster gains the ability to fly through the air (maximum speed: as fast as a swallow) and hover in mid-air. Changing directions or manouvering requires concentration.
(Base 15, +2 Sun)
Twin Corpse In(Cr)Co30
R: Touch, D: Sun, T: ind
This spell is cast on a physical arcane connection to a human (e.g. blood, hair, finger). It creates an physical copy of the human body the arcane connection belongs to.
(Base 10, +1 Touch, +2 Sun, +1 Creo requisite)
A window of singular direction InTe10 (HoH:TL p. 141)
The blocked passage CrTe20 (like Wall of Protecting stone, duration diameter)
Curse of Prenatural Growth or Shrinking MuCo15
Wizard's sidestep ReIm 10
Increased Arts (one additional year because I no longer have Talisman + wizard's hop)
In 9 to 10, Te 5, Im 5
changed exposure -8xp MT
Ironically, the character is a lot stronger now.
Question: Can I keep the background story (see old post - 15 years pg - but mechanically only 10pg)?
African, or European?
African 
Just realized something scandalous: my zombies are naked. So I'll have to replace curse of shrinking with the spellswiki spell naked man weaving!
Just be glad you don't have Restriction:Virgin on any human forms you create...
Make them female zombies. After all, men are naked, women are nude, plus it would be a great distraction to males on the field of battle and most fighting sorts are men in this day and age.