Krull
Krull was a tortle cleric of Tiamat. The death-priest conducted numerous experiments in Arkhan's Tower in Avernus in an attempt to control the Hand of Vecna wielded by Arkhan. He was interested in obtaining artifacts and creatures that might help with his experiments, such as an orb of dragonkind or a unicorn. Krull had his entire shell carved with runes of prayers to Tiamat in Draconic.
However, all of this was before Arkahn the Cruel betrayed his trusted lieutenant to further his agenda. Betrayed, shunned by his patron deity, and near to death Krull swore vengeance against his former allies and plead the universe to give him the strength to exact his revenge. At this moment the newly ascendant Bolana Triade of Vengeance heard his plea and lent him some of her powers. Using that power, Krull escaped Avernus to Arteria where he went searching for allies to help him in his plans in killing Arkahn and eventually Tiamat herself.
After finding such allies in the two adventurers of the Daybreakers, Hezandrius and Keolith , he is now working in their tower trying to amass more powers and weaponery that could even threaten a god using any means necessary.