Codex Alera. Book 2. Battle for Calderon

For the first time in a thousand years, the peoples of Alera united. They were forced to do this by the need to fight warlike alien races inhabiting neighboring lands. But although the Alerans have powerful helpers, the furies of earth, air, fire, water, wood and metal they have tamed, saving unity hangs by a thread. The aged ruler is unable to protect the country from invasions and nip the civil war in the bud, and now the fate of Alera is in the hands of young Tavi, just yesterday an unknown shepherd, and now a student at the most prestigious Academy, and his new comrades.