Apologies; you're right. Not sure where I had the idea of difficult lab totals from. There is a reference to the mysteries in the Rhine Tribunal, but those presumably aren't part of this particular path.
One oddity I note though; when studying Nature Lore (MC p.103), the Source Quality is related to the Aura of the Area. It doesn't say, but if faeries are not natural presumably this only works with a Magical Aura? Or would a Divine Aura also do (since perfect nature presumably has some correspondence to divine Creation)?
NB: I don't care if it'd work with an Infernal Aura, no character I'd want to play would be fool enough to go and live/study in one of those! (unless they wanted fire-breathing wolves, er, hellhounds, no, stop right there!)
I would treat the aura the same way as with magic. So it depends on what Realm is associated with your virtue. For most magi, that means a Magic aura would count at full value, while a Faerie aura would count at half value.
For a Merinita, both Magic and Faerie auras would count at full value.
And if you happened to be a Holy magus, then a Divine aura would count at full value.
Or something like that. 
Revised Arts:
Revised Spells:
Discern Images of Truth and Falsehood seems less useful than Summoning the Distant Image, but open to advice.
Tweaked Virtues & Flaws:
Mythic Blood is themed around Merinita herself, although she need not be the actual source, or known for certain even if she is. Humble chosen as corresponding personality flaw, brought out by the same events as Infamous (I almost went for Reclusive, but that's a bit too strong); Minor MF already discussed; innate power TBD but seriously considering Veil of Invisibility to generally keep a low profile. Also dropped Affinity Herbam for Inventive Genius, although Personal Vis Source remains tempting.
I'd suggest shifting some of the xp spent on the Arts (Cr, An, Te) towards abilities. Right now his Magic Theory is low for a Bonisagus. He has no Organization Lore: Order of Hermes (which would probably have a specialty in House Merinita), no Magic Lore, no Faerie Lore.
A few low-level utility spells would make him a lot better at outdoor life. Palm of Flame to light a fire, Cloak of the Duck's Feathers to protect you and objects from the rain, Disguise of the Putrid Aroma to avoid being attacked by wild animals, etc.
Iām working over some of these suggestions - he already had both Faerie and Magic Lore at 1, and his Magic Theory was bought up from the recommended minimum using a fair chunk of his Skilled Parens xp.
I was assuming that mundane skills and equipment would cover some of the utility spell functions suggested, while being less noticeably unusual - one reason for focusing on Survival, as we discussed before especially when backed by Intuition of the Forest. In previous editions it often paid to take spells at character generation which would be useful but too difficult to research in the magusā early career, rather than simpler spells which could be researched or sponted. Iām aware of the Penetration change at 5th Ed which makes lower-level spells much more important, but as this is not a combat magus thatās not a great concern either (my old group used to run stories with a certain amount of unavoidable combat, which is why I originally took a number of spells with some combat utility- breaking this habit has proven a conscious effort).
Iām also instinctively wary of not having at least some xp in most of the Hermetic and related skills; I can bear not to take Penetration, but not Concentration, for instance.
WIP!
A magus right out of Gauntlet is often strapped for xp, so concentrating on a limited number of Arts is often key to being able to cover all the bases.
In your case, Skilled Parens gives you an extra 60 xp that can be spent on Hermetic Arts and abilities that can usually only be purchased during apprenticeship. You still face some hard decisions and must decide what's important to your concept, and what isn't. Even small amounts of xp spend on unnecessary stuff can bite.
Some of the things I see that can be looked at:
- Multiple Area Lores (Rhineland, Durenmar, Rhine Tribunal) - are they all essential to the concept?
- Purchasing mundane abilities with xp from apprenticeship (Survival) - can more of that xp be spend before apprenticeship?
- Some peripheral abilities (Profession Scribe, Code of Hermes) - are they important for your concept?
- Some peripheral Arts (Creo, Animal, Terram) - do they contribute significantly to important spells for your concept?
None of these need to be changed, really. I'm simply looking at areas that seem (to my outside eye) less central to the character.
Iāve reworked the abilities and the result is a bit more streamlined.
Arts experience remains at 120 (the apparently standard half apprenticeship) plus affinity effect, I.e. all the Skilled Parens xp is going into abilities; Iāve managed to afford an extra level of MT.
Utility spells are trickier, as while there are quite a number with some appeal, he can only afford a two or three at most, and the disparate Arts involved are going to mean casting issues,which reinforces the value of Mythic Blood. Do you see any problems with this approach?
There looks to be a small discrepancy in the table for Abilities, as I'm counting 125 xp for apprenticeship Abilities, while the total at the bottom is 120.
Utility spells are often lower-level, which don't require much in the Arts. They are often cast with Fatigue initially, in non-combat situations. And indeed, Mythic Blood will help there.
Have you given some thought about what the special power for Mythic Blood would be? An utility power might be useful, since it would not require Penetration.
Iāll need to post an updated abilities listing when I get home in a few days.
As to the Mythic power, I was thinking of Veil of Invisibility, for the general ability to go unnoticed in moments of stress, in or out of combat, also simply not wanting to be noticed which fits with the mythic origin being Merinita herself. At a push, this could also be used on a grog?
If the Mythic Blood is themed after Merinita, why not something that allows your magus to speak with animals? That would be complementary to trees and free you from the immediate need to invest efforts into Animal.
Invisibility does not seem thematically linked to Merinita...
She persisted in making herself really difficult to findā¦
From HoH:MC:
...a whitehaired woman dressed in green traveled alone through the wild lands of Europe, often vanishing into the great forests without a trace of her passing, a woman without equal in nature magic. She could see everything that happened in these places, she knew every bird and beast that lived in them, she could take any shape she chose, and she could command the spirits of the very trees themselves. Yet she was not savage, according to those who had met her, but wise; a woodswoman and healer at home in the forest and perfectly attuned to the wild. She was also intensely shy, and said to only speak when absolutely necessary.
... Merinita obviously knew a great deal, especially about healing and nurturing plants and living creatures...
She eventually demonstrated the ability to join her mind, body, and spirit with an animal, and this was integrated into Hermetic teaching as the enchantment that binds a maga to her familiar.
To me that doesn't sound like invisibility was her thing. It was more communicating with animals and plants, moving in the forest unhindered, understanding nature spirits, etc.
Hm. Looking at MuCo(An), the "take any shape she chose" suggests some form of versatile shapechanging effect, but the given spells all describe a specific transformation (wolf for Shape of the Woodland Prowler, raven for Cloak of Black Feathers) - what would be the level cost for the ability to transform oneself into any form, presumably from a thematically appropriate range, such as woodland animals and birds? Thinking Range Personal, Sun duration, choose form upon triggering, i.e. re-trigger for a different form?
Even if I was to allow it, a general shapeshifting power would probably be too high a level for the Mythic Blood power. Considering the MuCo guidelines (a land animal is Base 10, a bird or a fish is Base 20) and the added flexibility would add 2 or 3 magnitudes in my opinion. That would put a general land animal transformation at level 30-35, while a truly general animal transformation would be at level 40-45.
From a game-balance point of view, Shapeshifter virtue allows one to take a limited number of shapes (based on the ability score). It is also a Major virtue. Allowing a sub-part of a Major virtue to give a better version of another Major virtue seems unbalanced.
So that's a no.
Didnāt think thatād fly, but worth asking, as thereās no equivalent guideline. I was unaware of that virtue, but the extrapolation makes sense.
So, need to pick a specific animal; probably something native to the Rhein woodlands and either unobtrusive or downright stealthy. Owl or pine marten suggest themselves at first thought.
A stag could also make sense in relation with Merinita, as it was her familiar.
No matter how long I think about that, transforming into something that those able to will hunt vigorously isnāt entirely appealingā¦ and the slightly-tempting Beast Of Outlandish Size would probably make it worse, since any sightings would be storied and draw more attention.