Lawrence Watt-Evans is one of those mystery authors that you see occasionally. Not that he writes mysteries, but that it is mysterious why you find so few of his books on bookstore shelves. There isn't a better Science-fiction/Fantasy author out there, but while other authors have ten or twenty titles on the shelf, Watt-Evans typically only has his two or three latest.
This is especially annoying because he writes such good series fiction and when you find a good series, you want to go back and read the ones you missed. The world of Ethshar is one of the best fantasy worlds I've ever read and each time I see a new one, I buy it immediately. The Spriggan Mirror is the latest one in the series.
In a previous book the hero, while casting a spell, accidentally created a magic mirror with an unusual property: every once in a while, a spriggan crawls out of it. What is a spriggan you ask? Well, a spriggan is a small, annoying, trouble-making humanoid. There were no spriggans before this mirror was created, but now, several years later, the world is starting to be overrun with them. Something needs to be done.
One of the good things about the world of Ethshar is the way that the stories mostly involve different characters, but common locales and history. There isn't one central person found in all of the stories, so you can read them in pretty much any order. The Spriggan Mirror follows a variation this pattern, where the hero of the previous book appears as a side character in the current one.
All, in all, it's a fun book, but not the best one in the Ethshar universe.