So having magic eaters spawn is always a fear for everyone. Would it be possible to make the effect extend to a small area for a limited time so that familiars cannot attract them? Or add some kind of "branch" version as to not use the already existing item and doubles as a bundle of Abjurer's?
Seriously just disable familiars triggering magic eaters.
I like the idea of this more for the general practicality than the specific use here. It would be great if using a nightshade in a campfire made a cloud that protected everyone much like the OP suggests. While I actually enjoy the need for little things like bedrolls, fires, food, nightshade... I don't think it's really a big deal to make a 'camp preparation scenario' easier for everyone.