Raven's shadow - Patricia Briggs

From #1 New York Times bestselling author Patricia Briggs comes a fantastical series set in a world where magic is the only thing that stands between humanity and total destruction...

Seraph is a Raven mage, and among the last of the Travelers who ensure that the city of Colossae is safe from evil. Unwelcome by those who fear magic, the wizard clans have been decimated by the very people they've sworn to protect. But Seraph is spared a similar fate by the ex-soldier Tier-and together they build a life where she is no longer burdened by her people's responsibility.

But now Tier is missing-or dead-and Seraph's reprieve from her duty is over. Using her magic to discover her husband's fate, Seraph realizes the prison that holds the evil entity known as Stalker is weakening-and only Seraph can fulfill her ancestors' oath...