I'm looking for some help in adjudicating the effects of Witch's Moon -- the equivalent of Twilight for Hedge Witches. As for Hermetic Twilight, one can have a "positive" or "negative" experience. Positive experiences lead to xp, new mystical virtues, or new supernatural abilities; negative ones lead to xp losses, or new supernatural flaws.
The problem is that, unlike with Twilight, there are no guidelines (say, 11+ Warping points gained leading to Major Virtues). Also, unlike Twillight which is triggered by particularly powerful bursts of magic (2+ Warping points gained) which makes it easy to "colour" the gain or loss appropriately, Witch's Moon is triggered when total Warping reaches a certain threshold making the cause more "generic" and the effect more difficult to adjudicate.
Any guidelines to avoid being completely arbitrary? This is particularly important for UnGifted Folk Witches, for which Supernatural abilities gained this way are truly much more of a boon than xp, since in this way they can sidestep the need of Initiations.
I would look at what was either the "most significant" or "most recent" cause of gaining Warping Points (since the last Witch's Moon). Alternatively, perhaps look at where she was when the Witch's Moon began, where she convalesced during it, or who she was with at the time (either during onset or convalescence).
I would say: 6XP = minor virtue if tyou prefer. 11+ XP = major virtue. Same for flaws. Fail by 6, minor flaw. Fail by 11+ major flaw. Would that cut it for you? We will have a witch as well in our next saga, so it might be interesting to see what your think about it.
Another thought might be what are they "becoming?" The Gruagach become more troll-like over time with each Warping. So what are your witches like? What is the inherent risk of witchcraft in your saga?
Maybe with each Warping they slowly become hook-nosed, wart-faced, hunch-backed crones with a predilection for eating children? Or poisoning apples?
For my interpretation, the Witches are generally community-oriented. So their Warping is going to affect that. Physically, they become more like icky witches in appearance. Mentally, they start to suffer from strange compulsions (newts! black cats!), paranoia, distrust and so on. Eventually, if they go real bat-crazy, they run off to the swamp, turn evil and live in a hut where they lure children to their dooms.