Dustlight. The Bacra Chronicles, #4

Six years after the fall of Anthora, a magical mishap throws Yana and Shan Goldtree from a Varaku hive into an unknown wilderness. As they search for a path home, their brother Tessen faces a tragedy that forces his family to leave their hidden sanctuary of Haven Cove. Despite disparate locations, the siblings and their diverse allies share the same objective: find a way to defeat a powerful enemy who will do anything to assert her supremacy, including destroying her own family.
The fallen Moonlight Guardian Lyssandra Zephyrain commands her legions of followers from Bacra's new capital, Crescent Vale. She has been quietly waiting for the right moment to strike those she sees as her enemies, and her patience has run out. With the help of her magic-skilled zealots, she will reshape the world to her liking-if her Spellkeeper collection doesn't figure out how to subdue her first.
One Spellkeeper in particular aspires to become a threat from within, but the young healer Saevel Yarrow's soft form of magic offers no offensive advantage against a foe whose power grows with each realm she devastates. It will take something far more drastic than a somnolent teenager's cottage witchery to save Bacra now. Dustlight is the fifth and final book of The Bacra Chronicles.