The Runes of the Earth by Stephen R. Donaldson

Ten years after the events of White Gold Wielder, Linden Avery lives quietly, raising her adopted son, Jeremiah. But when he is stolen away by mysterious forces, she is thrust once again into the magical Land—a place transformed and threatened by ancient evils. Torn between grief and duty, Linden must seek out the legendary Thomas Covenant and face the rising Despiser, whose power now threatens to unmake the world itself. As she journeys through realms both wondrous and perilous, the boundaries of time, love, and sacrifice blur in a struggle that will determine the fate of all creation. The Runes of the Earth marks the triumphant beginning of The Last Chronicles of Thomas Covenant, a saga of epic vision and emotional depth.