Dragon Heist Remix - Part 4D: Xanathar's Lair
Xanathar stole the Stone of Golorr from Lord Neverember and he stole one of the three Eyes from the Zhentarim. Then he lost the Stone when Dalakhar took it from him. As a result, once the PCs become truly involved with the Grand Game, it is likely that Xanathar is on a level playing field with Manshoon and the Cassalanters, holding but a single Eye.