[@Moonlit Sonata]
Yeah I can understand why A might have been going a bit too far considering the brief nature of the story. 

Basically that's the idea behind it yeah, might have phrased it poorly. It's rather vague whether or not she was actually one of the people who participated in making them drunk / stealing their stuff, but she was the reason for that happening and had great success with it because of the help from the other slave girls. Because of it, it's not really something she'd be using alone, and would be stronger in the presence of a Sister. 
Concerning the medium, I'm not sure on what would be practical. I'm considering maybe pheromone-based, hence giving it a more "clear" reason for why it's active / amplified in the presence of others? 

The 'killing intent' part seems a bit different from what I had in mind, since it sort of goes against the idea of it being based on the reinactments that followed in the festivals after the event. Also, it would be rendered pretty useless against non-sentient creatures if that's the case. I'm fine with it not being exactly useful against mental attacks, which is why maybe something like active attempts at physical harm being nullified could work better. If there is anything strong enough to bypass it, then they'd likely have clauses for it on their own NP to deal with this type of field.