The Rill Lord (The Triempery Revelations #6)

The final battle is here.
--------
The Wall has been destroyed--and magically restored--by Dorilian Sordaneon. Instead of a hero's return to Prince Handurin's army, the Kheld and Esseran troops are mutinous, fearing Dorilian’s newly revealed powers. The rift allows the sorcerer Nammuor to spring a deadly trap.

When Handurin and Dorilian finally engage with Nammuor’s sorcery, the full powers of both sides are revealed, unleashing both desperation and cataclysm.