The Sellswords Series Servant of the Shard by R. A. Salvatore 2000 Hardback

The Assassin Surrounded by dark elves, Artemis Entreri tightens his grip on the streets of Calimport. While he urges caution, his black-skinned sponsor grows ever more ambitious. The assassin will soon find himself on a path his most hated enemy has walked before him--a path that leads to a place where someone like Entreri would never be welcome. The Drow Jarlaxle has ascended from dark Menzoberranzan with only evil intentions. The malevolent Crystal Shard's influence on him intensifies until even the drow agents he brought with him grow fearful. When Bregan D'aerthe itself begins to turn on him, Jarlaxle will be forced to find a savior in the man he's come to enslave.