Little is known about Casmir's career before he joined the Conspiracy, but he seemed to specialize in the darker forms of Thaumaturgy and of sacrificial magic that required torture and domination. He enjoyed using his thaumaturgical powers to torture mortals, forcing them to do things against their will while tempting them with knowledge about the dark arts. Casmir was very protective of the ways of blood magic and only shared them with his blood bonded progeny. He also spoke in a quite antiquated language, even for the the 15th century, and seemed to hold Gangrel in disdain for their savage ways.
It is uncertain how long he survived after the Conspiracy's success in 1444 CE. However, given that he acted against Clan interests with his involvement in the Conspiracy, and that the Tremere do not take traitors lightly, and his childe was forced to flee and assume a different identity, it seems probable that he did not survive for long.
- His portrait in Giovanni Chronicles I: The Last Supper is actually that of the real life Pope Leo X. It does not match his physical description in his character sheet, where he is described as a portly man with a large white beard, wearing a black robe with silver trim.
- While he is shown using the Path of Corruption in the scenario of the same book, his character sheet does not list it as one of his used Paths.