Érzsebet was a dedicated occultist and practised magick since many years ago. One source claim she knew how to chant old bohemic songs and the wolfes sung with her. She consulted witches and so on. I don't know how much truth it is behind the blood magic practise, but eventually she had a strong belief in the power of the blood which is not unusual since both religious practise and antropology give evidence in mankinds belief in the power of the blood. As a rather expensive habit Érzesebet started to use the blood of local virgin girls to keep her skin from ageing. Local farmer girls from the villages nearby came into her service. The theft of their vitae was not enough, she aslo had to humilate and torture them under sadistic circumstances. She bathed in their blood, rubbed it into her skin. She even used their menstrual blood. But she was ageing still...and learned from her witch in service that the blood of local peasant girls was not enough. She need "blue" from noble virgins....