And following on heterodyning, I'm wondering if it's going to turn out to interfere with wasps. It blocks Lucrezia in Agatha's head. When we get Lucrezia's POV when the locket shuts her down, she hears it as a sound - I think they use the word "whine", but that's not too far from "atonal drone".

The counter-argument to this is that all the revenants in Sturmhalten were still rampaging while Agatha's signal was running. On the other hand, the city didn't really go to hell until after it was shut off. I could think of a couple of ways around that.