Kostacki is an Irish Master of the Night. In the Early Middle Age he was leader of the Picts alongside Lord Marsden. Around the beginning of the 1900's, he apparently went mad and started ruthlessly killing people in Cornwall, hiding in the former mansion of Amber Tremayne. Kostacki's actions were about to break the Masters' rule of not openly reveal themselves to mankind. In order to prevent that, Amber and her brother Draka fought against Kostacki and eventually dismembered his body and nailed the pieces under the sea, leaving him alive but unable to cause damage.