Amie Kaufman - Scorch Dragons (Elementals #2)

After the fateful battle between the ICE WOLVES and the SCORCH DRAGONS, Anders and his twin sister, Rayna, have been reunited. But there's no time for celebrating. In the mountain stronghold of Drekhelm, Anders and his wolf friend Lisabet are seen as threats, and only the leader of the dragons can keep them safe.
   When the temperature starts to drop all over Vallen, they learn the wolves have stolen a weather-altering artefact called the Snowstone, and every dragon, including Rayna, is now in deathly danger. Desperate to broker peace, Anders enlists the help of a few new flame-breathing friends to stop the wolves' next plan of attack.
   Together, these former rivals must go on a dangerous quest to find the scattered pieces of the Sun Scepter, the only artefact that can counteract the Snowstone. Because if either device goes unchecked, all hope for a truce will be lost.
   In the second book of New York Times bestselling author Amie Kaufman's heart-stopping adventure series, the struggle for power is at an all-time high and the lives of Anders's friends on both sides of the conflict are at stake.