The Lost City of Ithos: Mage Errant Book 4

Half a millennium ago, the sphinx Kanderon Crux and her allies banished the city of Imperial Ithos from the world of Anastis, in a desperate attempt to defeat the Ithonian Empire. Her dread weapon, the Exile Splinter, even erased the memory of its location from the universe. Now it's returning, bringing the Exile Splinter back with it. The great powers of the continent are desperately hunting for the site of the lost city, knowledge lost even to Kanderon herself. None know what ancient Ithonian weapons and enchantments might still be… more