Three Katherines of Allingdale: Masses of research and plot-wrangling going on, though little enough actual writing. The Wassail Arc is going through some serious changes, in the course of being drawn taut into the line of the plot. By far the biggest change sorts out a number of my other problems simultaneously - it's now really the Fairfields Arc, spanning almost a year from the Wassail until the approach of the next winter. Much of that year is going to be skipped over or alluded to only in passing. That still gives time for a number of things to develop organically.
Most of all, it gives Katy Elflocks time to try to deal with the situation her own way - and actually fail, learning first-hand what sort of impossibility she's up against this time. That's really far more in character than deducing a lot about the Big Bad in advance, so Kate and Luke can convince her and her circle that it's time for desperate remedies already. And I get to do big reveals in action rather than exposition!
I couldn't do that the first time around, because they hadn't been fully revealed to me either.
Also, Fairfields' military strategy in Langdale now looks at least roughly plausible - they actually do logistics, and get time to set up the anvil for their great stroke at Carrowglaze in a less handwavy manner.
Here I go again...