Their first album 1614 is a conceptalbum (with some artistic changes) about the life of Elizabeth Báthory (nicknamed Blood Countess) who was a Hungarian countess. She has been labelled the most prolific female serial killer in history, though the precise number of victims is debated. Later writtings about the case have led to legendary accounts of the Countess bathing in the blood of virgins to retain her youth and subsequently.

Opera Diabolicus is the brainchild of composer David Grimoire and lyricist Adrian de Crow. The idea sprung to life when the two of them met randomly at a stage play of Umberto Eco's book. The Name of the Rose at a theatre in Gothenburg the year 2006. Both of them were very intrigued by the story and they ended up talking about how interesting it would be to make a theatrical and dark metal musical based on that kind of a story. The conversation between them that took place in Gothenburg planted the seed that soon should grow to be the concept of Opera Diabolicus - The concept of combining the dark elements of music and theatre in alliance with musical excellency.