Legends of Shannara. The Measure of the Magic: Terry Brooks

For five hundred years, the survivors of the Great Wars lived peacefully in a valley sanctuary shielded by powerful magic from the dangerous outside world. But the enchanted barriers have crumbled, and the threat of annihilation looms large once more. As he lay dying, Sider Ament, bearer of the last black staff and protector of the valley, gave stewardship of the powerful talisman to the young Tracker Panterra Qu. Now the newly anointed Knight of the Word must take up the battle against evil wherever it threatens: from without, where an army of bloodthirsty Trolls is massing for invasion; and from within, where the Elf king of Arborlon has been murdered, his daughter stands accused, and a heinous conspiracy is poised to subjugate the kingdom. But even these affairs will pale beside the most harrowing menace Panterra is destined to confront - a nameless, merciless agent of darkness on a relentless mission: to claim the last black staff and the life of whoever wields it.