Web of the Witch World

Andre Norton enthralled readers for decades with thrilling tales of people challenged to the limits of their endurance in epic battles of good against evil. None are more memorable than her Witch World novels.
The Kolder linger on, a constant threat to Simon and the witches he's sworn to protect. To save their world from this threat from another dimension, Simon and Jaelithe must venture to the heart of the poisonous Kolder realm and vanquish them for good, or witness the enslavement of their world.