Arkhan The Cruel

Arkhan the Cruel was a dragonborn priest of Tiamat.
After a brief visit to the world of Exandria, Arkhan replaced his left hand with a legendary artifact known as the Hand of Vecna, with the intention of using its power to free Tiamat from her prison in Avernus.
By the Year 1587 DR, Arkhan, having taken residence in a tower located near a monument dedicated to Tiamat in Avernus, had yet to succeed in his endeavor. Prolonged possession of the Hand of Vecna was slowly causing his left side to become corrupted, a process that could only be slowed down by sacrificing the life of good creatures.
He entered into a deal with the Savage Seven to obtain a unicorn as a sacrifice in exchange for the blood of Tiamat in his reliquary. He also suggested a possible alignment with them against Zariel, archduchess of Avernus.
After receiving the unicorn, Tiamat offered her help to destroy the chains of Elturel and Arkhan's help against Zariel if battle ensues.
When the Savage Seven were forced to battle Zariel, he teleported in with his minotaur companion Torogar Steelfist and helped them destroy her. Arkhan now vies for the title of Archduke of Avernus.