Khazan

One of the men employed by Strahd to raise Castle Ravenloft was an archwizard named Khazan. After his work on the castle was complete, Khazan retired to the Barovian valley and built a tower for himself on a small island on Lake Baratok. With the help of some engineers and laborers, he also built an earth-and-gravel causeway connecting the island with the nearby shore.
In his waning years, Khazan visited the Amber Temple (chapter 13) and discovered the secret to becoming a lich. He returned to his tower and was able to complete the transformation. Some years later, after Strahd became a vampire, Khazan paid a visit to Castle Ravenloft with the notion of challenging Strahd for rulership of Barovia. Instead, much to Khazan’s surprise, Strahd persuaded him to serve as an advisor in matters of magic. When not advising Strahd, the lich spent most of his time in the Amber Temple, trying to master the secret of demilichdom in the hope of finding a way to magically project his spirit beyond the confines of Strahd’s realm. His efforts failed, and Khazan destroyed himself. His remains lie entombed in the catacombs of Ravenloft.
Khazan’s tower stood empty for ages, it seemed, and would have collapsed under the weight of neglect were it not for the magic wards placed on it long ago. Recently, the tower was taken over by the legendary vampire hunter Rudolph van Richten, who used it as a base from which to explore Barovia. He has since relocated to the nearby town of Vallaki, where he hides in plain sight.
Khazan warded his tower so that he alone could cast spells near or within it. The effect is identical to an antimagic field centered on the tower and extending 5 feet from it in all directions. The effect doesn’t apply to magic traps and constructs created by Khazan, including the trap on the tower door in area V2, the golems in areas V4, and the animated suit of armor in area V7.