Zhivris

An ageless Dark Power native to the Plane of Shadow, Zhivris was once a higher being who preyed on souls within the veil of the Gloomshrouds. In the Pre-Unified Age, he was locked into an amber sarcophagus by high mages of the Azure Paragon, then was stored in the Amber Temple alongside other Dark Powers. Claiming the title "The Overgrowth," Zhivris asserted to have ultimate power over corrupted plantlife, but was only able to influence the realm beyond his tomb with minor magic. 

As his powers waxed and waned during the Barovian Calender Timeline, he contacted adventurers to harvest soul energy from Barovians. He looked to feast on souls killed by thorns, briars, and vines, and in exchange for magical power, would request that their champions destroy his sarcophagus. However, he experienced few successes, as souls leaving Barovia were nearly always consumed by Vampyr, and his champions were killed by the many horrors of the valley.