Okay, you were all extremely helpful a few days ago in getting me to think about this title in a different way.
I want to say that up front, because the titles that have occurred to me now don’t use any of your suggestions directly. Nevertheless, thinking about “light” and “moon” and so on gave me a different direction.
I wrote down all your suggestions and related two-word titles that occurred to me, about a dozen total, and gazed at them. I started with Blood Witch — my first idea — and added False Witch and Witch Moon and Moon Bound (too cliched, I know!) and Moon Rising and so on. Also Light Rising and Binding Light and things like that.
Then I gazed at the current titles: Black Dog, Pure Magic, Shadow Twin, Copper Mountain. All of those have either adjective-noun or noun-noun, so I decided I had better make the second word a noun. The first word seemed to allow more flexibility. So I tried titles involving Light, including Dawn Light and Rising Dawn and Rising Light
Then I thought about the number of syllables. One-one, one-one, two-one, two-two. So there isn’t a really rigid requirement for number of syllables, just number of words.
THEN I thought abut stuff that is important all the way through the series and can be assumed to be important for Book 5 as well, or if necessary made to be important — at least important enough to justify inclusion in the title. Not only things like demons, but things like — mandalas, pentagrams, spirals, circles.
So now I am thinking of this for the fifth book:
Or some other two-word title with mandala in it.
There, that is a LOT less evocative of horror. Whatever happens in Book 5, I expect mandalas will be drawn. What do you all think?