Whenever would be most convenient for our purposes. Fray can have it whenever he needs it, and we'll say that's when we got word from Tasia.
Scott
Harnessing can be learned by non-Mutantes, but they have to be taught it as a spell mastery specialization, and they have to be taught by the Mutantes--see the next-to-last paragraph on the same page. (The text refers to spell mastery "abilities", but I assume that's an error in terminology.)
Scott
Wishbone rather than Fray, but I don't think that changes anything.
There's a little bit of Harnassing already integrated into Hermetic magic - that's why various Muto Corpus spells include props (such as the raven feather cape Cloak of Black Feathers) that you can use to cancel the spell at will. But I think we're agreed that anything similar outside Muto Corpus spells requires some version of the Mutantes special abilities (whether that's via Harnessed Magic, Mutantum Magic, Tamed Magic, the Mastery etc.).
I mucked up the level in the description, its a MuAn25 already. I plan on using FFM to get to R:Voice, or down to R:Personal for himself, or using it through an Intangible Tunnel against foes which are a long way away (Fray made a sight based OTIT recently so he can cast spells at much further distance).
Its intended to be cast on anything, including the caster, however the normal rules for casting through Parma would apply (unless Fray uses FFM to alter the R:Personal). Any animal is a valid target if they are size +3 or less, and than would normally include creatures which have been transformed - thats a normal part of magic as I understand how the valid targets interact with magic. It does mean that Fray can't use it on himself unless he is already transformed, so its not perfect.
I guess the "holding the item" is probably only valid if the caster is also the target, because most animals without Int wouldn't have the presence of mind to understand the use.
I was thinking of three uses - stopping opponents which are animals by making them suffocate as a fish - like the horse a rider is using, beating that Princely Horse should it come to it to keep the deal with the locals around the covenant, and Fray using it to transform from one animal form to another so he can swim in rivers and such.
Horses of enemies was a use I was thinking of, but I agree it should also work for transforming people who have already been shape-shifted into animals. We do still have a big lake in the covenant we haven't explored properly (although given that that has something large living in it, that's a risky plan).
It occurs to me that it might be worth repeating the relevant Deprivation of Air guidelines in the spell.
I think I am coming down more firmly on "inbuilt cancellation is only an option under Muto Corpus, not Muto Animal", though.
Moved this comment on game theory out of the story thread
I like the idea it's slightly forgiving, and mostly circular. Wizards tracing circles in the ground won't be perfect, but should be approximate. Mostly-spherical domes is the way I see them. If you move one to a wall, then it will look like a porthole. That said, seems fair to allow the domes to also be stretched high, so that a Magus can use a Ring a pace wide to stand in, but that ring will also be 2-3 paces tall so they can stand upright.
So not viable as pyramids or cubes, but otherwise domes with forgiveness?
Seems odd that a Magus who is transformed into a beast can't hold an object in the same way a human can hold an object. What is the real difference?
My lion shape holds the fishbone in its mouth as it transformed, is just s valid as a human holds a trinket in their hand and becomes a dog.
I don't think there's any reason it's fundamentally impossible. However, the Mutantes who first brought the concept in only integrated it for Muto Corpus. It would probably require a Minor Breakthrough to extend it reliably to another Art (and you could probably then build on that to build it into Muto spells more generally), although you could probably get it as a one-off for specific spells via experimentation.
Edit: Found it in HoH-TL, p97 talks about Mutanes bringing Muto Vim into the order, and the same Magus who did that was a master of transformation (bird, fish, wolf). Mid way down the page.
If the rule of the game is that applies only to MuCo then ok, I'll update.
I'm not sure whether you're agreeing with me or disagreeing there? I certainly don't think that that shows that you can do other forms - firstly, those were probably all Muto Corpus spells (albeit with an Animal requisite), and secondly the Mutantes can cancel any of their magic anyway, so the forefather of the Mutantes cancelling his spells wouldn't mean random magi can.
I think the most relevant paragraph is:
Triceres’s great-grandson took the Hermetic name Mutantus after his master died, and continued to experiment with Muto, which came quite easily to him. In particular, he studied transformation magic, and developed several spells that incorporated his great-grandfather’s unusual ideas. They allowed him to cancel a spell after casting it, without waiting for the duration to end, and by 1220 this concept has been integrated into a basic function of Muto Corpus spells, though most magi are not aware of the greater implications.
Ultimately, though, is a call for MTKnife.
I wasn't in agreement at all when I first read your view - which is why I asked if it was cannon. But then I went looking through the books and found the entry.
So now I agree fully. I've edited the spell in Fray's description to not have that option at all, and checked his other MuAn transformation spells so they don't use it too. I guess my knee-jerk reaction was thinking it *should, but I respect the cannon - you were dead right.
Ah, thanks.
Well, if Fray is ever looking for an Original Research project...
Been pondering that - its a good idea. Was also thinking a new Range, Duration, or Target would be a good choice with his FFM virtue (T: Pair) or trying to better integrate some of the Mutanes virtues into regular hermetic magic.
...which is always a great idea for a saga focused on exploration.
Scott
Greetings Gentlefolk! Salve Sodales!
I will shortly be introducing Shuba to the saga.
Kind Regards
Ivan
Heya, Ivan. 
Scott
Happy Christmas!
Thinking about future adventures - MTKnife, do you have anything specific you want to do next with Viola?
Stay in her lab...forever.
She might want to have children at some point, which is one reason she's avoided a longevity potion (the other, more important reason, being the Warping), but there's a hurdle there that may be difficult given her personality.
In the end, she's probably going to have to be dragged out in some way.
Scott
I am going to leave any romance plot lines to someone else (or handwave them off screen). I suppose I might manage something more politically motivated, but that may not be what you're looking for.
(Amusingly, I've had vaguely similar thoughts about getting Gregorius married and having children before a longevity ritual occasionally, although those have been mostly along the lines of either going to Translyvania for a rotation and coming back with a wife or making a political marriage locally).
I will have a think what to do with Calliope. Or possibly that Faerie Friend Viola theoretically has.
I don't suppose anyone else is feeling romantic, not that it has to be done immediately? If only there were Tinder for Magae....
The Faerie Friend is a good idea--we've put off designing him/her/it for too long. 
Scott