The Demon Tide by Laurie Forest — book slip

Newly exposed as the Black Witch of Prophecy, Elloren Gardner Grey is on the run, unsure if she’ll find friends or foes. With her fastmate, Lukas Grey, either dead or in the hands of High Mage Marcus Vogel, Elloren knows the only chance of turning the tide of the coming war is to seek allies who will listen long enough not to kill her on sight.

In the Eastern Realm, Water Fae Tierney Calix and Elloren’s brother Trystan have joined the Wyvernguard to prepare for Vogel’s attack. But Trystan is fighting on two fronts, as the most despised and least trusted member of the guard. And Tierney’s bond with Erthia’s most powerful river has exposed a danger even more terrifying than the looming war.