Way of the Wicked: Revenge of the Forsaken
Daemon prince and arch-deacon in service to the lord of pestilence
Vetra-Kali is a powerfull and ancient leukodaemon, a harbinger of pestilence and a high servant of the Pale Horseman. He was also the architect of the Horn of Abbadon and the Sons of the Pale Horseman.
Eighty years ago he was slayed by the Victor and barred access to the mortal realm via a holy artifact of Mitra called the Silver Seal.
The Nessian knot managed to summon him and get the Tears of Achlys from him, they then used a wish granted to them by the daemon to banish him forever.