Storm Breaking — Mercedes Lackey

ANCIENT MAGIC

As mysterious, magical onslaughts ravage Valdemar and the kingdoms of the West, the western allies have traveled far to locate the ruins of the Tower of Urtho, Mage of Silence, and excavate his legendary Vault, hidden stronghold of some of the most powerful magical weapons ever devised. They now know that the mage storms are an "echo" through time of the prehistoric Cataclysm which permanently warped their world more than two thousand years ago. If they don't find a way to stop these magical vibrations they will culminate in another Cataclysm --this time destroying their world for good.

But Urtho's Vault is not the only thing buried below the Dorisha Plains, and camped in the ruins of what was once the workplace of the most ingenious mage their world has ever known, the desperate allies soon realize that their solution may lie beneath their feet. The saving of their world just might be accomplished by the work of a man who has been dead for millennia!