"Beware the unanswered riddle."
I just finished Heir of Sea and Fire, book #2 of Patricia A. McKillip's Riddle-Master Trilogy.
By the unconquered Kings of An I had forgotten how brilliant this book was and is, and that oath stirs quite a bit a trouble in a land where ancient grudges will pull themselves, bones and all, from the grave. Including a sea-born sorrow that makes Raederle of An quite the riddle herself as questions and wizards move to the destroyed Wizards City. War is coming, one that even the hate-filled dead have a stake in. A war that will test the very strictures of riddlery.
"Beware another riddle-master."