Complex sentence: The pair recover Uma to the abandoned witcher school of Kaer Morhen, and Yennefer successfully removes Uma's curse, revealing him to be Avallac'h, who informs Geralt that he teleported Ciri to the Isle of Mists to save her from the Lofoten attack.
Split into simpler sentences: The pair recover Uma to the abandoned witcher school of Kaer Morhen where Yennefer successfully removes Uma's curse, transforming him into Avallac'h. He reveals that he teleported Ciri to the Isle of Mists to save her from the Lofoten attack.