The beholder Xanathar, Waterdeep's most infamous crime lord, is known to hoard information on friend and foe alike. He catalogs lore about adventurers and ponders methods to thwart them. His twisted mind imagines that he can eventually record everything! Assembled here for the first time are a set of new rules and story options for all the character classes in the Player's Handbook, including over twenty-five new subclasses. The book also presents new spells for both player characters and monsters. Dungeon Masters will find new rules for traps, magic items, downtime activities, and more -- all designed to enhance a D&D campaign and push it in new directions. Amid all this expansion material, the Xanathar offers bizarre observations about whatever his eyestalks happen to glimpse. Pray they don't come to rest on you!