After he and Erevis were pulled into a near-death experience at the hands of a shadow adept and his slaadi partners, they grudgingly joined forces to oppose them. During this period, Riven and Cale became the first and second of Mask's five mortal servants and were sometimes known as the right and left hands of Mask.
Riven was Mask's Second, following Erevis Cale as his friend and associate. As Mask's second of five, Riven was imbued with certain skills reminiscent of a divine champion, including a shadow-based lay on hands, and divine wrath which causes his sabers to bleed shadow. He was also given the Black Speech which, when spoken, causes anyone within earshot to experience nausea and pain.
Riven was a devout follower of the Shadowlord, and the caretaker of his temple which was stolen from the mad god Cyric. This temple was magically moved by a Githvyrik sorcerer named Vhostym to the Wayrock where it still stands.
Riven was a cold-hearted and efficient killer, and never showed any sympathy towards anyone or anything other than canines. Riven's eye was lost in a beating he received from an Amnian nobleman who was the slave master of Riven and his mother when he was a child. Riven was a kennelboy at the time, which was how he acquired his affinity for dogs. He became an exarch when he inherited part of Mask's portfolio (shadows) after the battle with Kesson Rel.
In 1484 DR, Riven had become the primary "avatar" of Mask's power, receiving the prayers of the few people still faithful to the Shadow Lord, as well as receiving thoughts not of his own mind, but rather from what remained of Mask. Following the instructions of Mask, Riven orchestrated several events with the intend of resurrecting the Master of all Thieves, and thwarting the plans of both Mephistopheles and the goddess Shar. Doing so by pushing the son of Erevis Cale, Vasen, into releasing his father from his prison within the Nine Hells, as well as releasing the remains of the Shadow Lord's divinity within Mephistopheles, Erevis, and Riven himself.
Upon the release of the remaining divinity of Mask, Riven chose to take up the task of becoming the new incarnation of the Lord of Shadows, thereby allowing his old rival to stay and start a life with his son Vasen.
- Dragon (magazine) #277.
- Dragon Magazine #297 p72
- Paul S. Kemp (November 2005). Midnight's Mask (MMP). (Wizards of the Coast), chap. ?. ISBN 978-0786936436.
- Paul S. Kemp (July 2003). Twilight Falling. (Wizards of the Coast). ISBN 0-7869-2998-7.
- Paul S. Kemp (December 2008). Shadowrealm. (Wizards of the Coast). ISBN 978-0786948639.
- Paul S. Kemp (March 2014). The Godborn (MMP). (Wizards of the Coast), chap. ?. ISBN 078696541X.