Thirteen

Kelley Armstrong's thirteenth and more-or-less final book in the Otherworld (formerly Women of the Otherworld) series is named, with admirable simplicity, Thirteen.  It completes the sub-trilogy begun in Waking the Witch and Spellbound, with the main narrator again being the young witch/sorcerer/demon hybrid Savannah Levine.  As before, I refuse to even attempt to summarize Savannah's backstory.  Read the novels.

I have to give Armstrong some serious props for actually ending her series before it jumps the shark and for doing it with a pretty creditable bang.  I won't say that every previous character shows up at some point, but she tags all the major ones at least briefly, with many of them narrating a chapter or two, and in general she ties up all the loose ends and everyone lives more-or-less happily ever after or dies very messily, as the case may be.