I needed something between the latest events I had outlined and the climax of the story. Just something. . . to keep the ending from being too abrupt and nothing more, I thought.
With some random inspiration, I set out, and found my heroine trapped in a situation with an evil witch.
I reflect that I hadn't given her a heavy-hitting spell to deal with such a powerful witch. Attempts to call for help and twist her own magic back on her didn't seem suitable. Wrestling with revision and what would be plausible to have her have learned before this -- realizing I couldn't revise the scene out, because bracing herself for this is how she works up the courage to do what needs to be done at the climax.
Twist, turn, try and try again. . . .
I think I have a way for her to use a spell I've already given her ingeniously enough to deliver her from danger. Let's see if it works out.