The Fall of Waterstone — Lilith Saintcrow

An elemental witch and her shieldmaiden navigate a dangerous world of forgotten myth and deep magic in the second volume of New York Times bestselling author Lilith Saintcrow's sweeping Norse-inspired epic fantasy series.

Solveig and her shieldmaid have finally reached the fabled Elder sanctuary of Waterstone -- a city of healing, restful beauty hidden from the Enemy's gaze. Yet whispers race through the palace halls, and those they have come to tentatively trust have hidden intentions. For not only is the city a refuge for an elementalist, her protector, and a mortal prince, it also holds a great weapon, one that only Solveig's kind may wield.
 
Yet Sol's faith in her own magic is perilously fractured. She can rely only her wits and skills of negotiation to be heard, or she will become a pawn in a dark game played by Elder and Enemy alike. The lord of the Black Land is mighty; treachery slithers amid Waterstone's many wonders, and time is growing short.
 
Before the darkness finds a way in, Sol must decide who to trust, where to turn for aid, and if she will take up a power she cannot hope to control. Even the right choice may doom not just the home she has left behind, but the entire world…

Black Land's Bane 
A Flame in the North