Books like The Morrigan's Curse

In this third and final book in the series that VOYA recommends “for fans of Percy Jackson and Harry Potter,” the war over the Eighth Day continues—and there’s more at stake than ever before.The battle between Kin and Transitioners that’s been brewing for centuries has come to a head. The sinister Kin have captured Addie Emrys, Evangeline’s sister and the Merlin descendant who will allow them to reverse the Eighth Day Spell and free themselves. Addie, who doesn’t realize the full consequences of her cooperation, is helping the Kin because they let her use her magic—something Evangeline never did—and the feeling of power running through her veins is impossible to resist. Meanwhile, Riley, Evangeline, and Jax craft a plan to rescue Addie from her captors. But the Kin’s unstoppable magic, plus the fact that Addie may not go willingly, force Riley to reconsider whether saving Addie is worth sacrificing everyone who lives in the seven-day week. Jax won’t accept letting Evangeline’s sister be used as a pawn, so he risks it all in a secret mission of his own. With the Morrigan pushing both sides of the war toward annihilation, Addie must decide with whom to stand, while Jax, Riley, and Evangeline confront the possibility of losing Addie to save the world. Adventure, action, and magic collide to create an unforgettable conclusion to the trilogy that Kirkus called “an inspired series.”