[scribbled on the back of the original letter]
William,
Merlin, okay, I'll try and get to it as soon as possible, I don't think it should be left there for long, regardless of undead house elves and things. Am with Gerard & Jon right now, + students, just outside of Forbidden Forest. Astronomy Professor in library.
Will owl Brendon afterward, or if the rune doesn't want to be broken (do feel like Herbology-tuned magic can help, but may have just been lucky). Probably best not to freak anyone out unnecessarily right now.