The Shepherd's Crown by Terry Pratchett

Some people live such lives of integrity, honour, wit and compassion that their absence leaves a voice in the universe that cannot be easily filled. When one such person on the Discworld dies, triggering continent-wide remorse, their enemies find that hole and pour through. The elves are back, and they have unfinished business...In an interview in 1995, Terry Pratchett said he found the idea of writing "the last Discworld novel," to be disconcerting. Though he always underestimated how many ideas he could mine from the setting (declaring in The Discworld Companion in 1994 that he doubted he'd still be writing regularly in the setting five years hence), he always saw it as a toolbox and a world he could continuously return to even after hiatuses. In the event, there were no (or very brief) hiatuses, and he would only reluctantly write "the last Discworld novel," its forty-first installment, a full twenty years after that statement.The feeling permeates The Shepherd's Crown that…