I'm been reading through the realm of power magic book and came across the virtue unaffected by the gift. The description says "The character is not affected by the negative effects of The Gift or Magical Air in others. Even a Blatant Gift does not especially bother the character."
Naturally the first thing I thought was that this could serve as means to allow for large communities of non hermetic gifted individuals and not have them implode. Then I thought what if one of the many rival groups of the order of hermes had an initiation script that could grant such a virtue.
Which leads me to my question what if Damhan-Allaidh during his conquest of the british isles had developed a script that grant unaffected by the virtue to his followers? How would an alliance composed of all magical traditions native to the isles function? It's mentioned that the spider wanted to establish a chiefdom of magi which is probably as close to magocracy as well ever get so how would that work? Would this "unified" group be able to keep the order out of the isles?
Some traditions, like Gruagachan and Learned Magicians, can already hand out Virtues through Give Blessing or Succurro Fortunam effects. If they know that Unaffected by the Gift is possible they can probably give it to themselves or others. That doesn't match how those traditions are described as interacting, though, so that already needs to be addressed.
I think Damhan-Allaidh had access to Gruagachan powers, and if not he certainly had followers who did so. You could just use that as the excuse as to why he was able to organize his followers without that imploding.
Generally speaking an initiation script for anyone without the Gift requires accepting some kind of flaw in order to gain the benefit. I can't see large numbers of people accepting most flaws just so they won't be suspicious of a group of people that they "clearly" have reason to suspect.
I mean we already have canonical Raudskina (hope to spell it right) and Order of Solomon. They work good enough even without this addition.
I also think Spider defeat is more about him already collect all groups who want team with him. So this script/initiation is not this big deal for this conflict.
If it was an initiation script, and this was for a community who all intended to undergo the mystery and didn't expect to interact with outsiders regularly, I'd give Magical Air along with Unaffected by the Gift - I think it's thematically appropriate, and it's also very isolating, which makes them more reliant on the person doing the initiating, and the group (cult) as a whole.
I would think something more along the lines of oath of fealty or vow- something which is a flaw to the people taking the initiation but useful to those offering ot, and likely something those undergoing the initiation won't take seriously until afterwards "okay, so I have to promise to do what they say, not like I'm going to do it."
Man, if only there was a word for when someone has a certain thing they can/cannot due that they think won't be that big of a deal only for it to magically enforce itself until the caster gets what they want...perhaps something from the same region as The Spider himself...
But for real, the idea of people being put under a Geas by someone offering "Unaffected by the Gift" is so fun with how the Gift people you think you're up to no good, doing underhanded dealing even if you aren't, and here comes someone who's doing underhanded dealing for the sake of people not being perceived as underhanded dealing. Especially since the INEVITABLE end of that is some sort of Poetic Justice being visited on The Spider for his trouble.
I'm not saying the initiation has no effect, I'm saying that people who are unfamiliar with how magic works might believe it has no effect when they sign up for the initiation.
Also, depending on perspective, one may say the initiation fails if they do not take the vow or oath of fealty seriously; or the initiation does take effect, and they magically Must take the vow or oath seriously now.
My assumption was the second, based on a lot of ancient rites being based on orthopraxy rather than orthodoxy, suggesting that it is what you do rather than what you intend that matters...
Also it's way too easy to argue with a SG about what your character intended