Originally released in 2010, Nightmare would serve as the fifth full-length from Huntington Beach, California metal mainstays Avenged Sevenfold. Marking the band's first album to be completed following the tragic and untimely loss of drummer Jimmy "The Rev" Sullivan at the end of 2009, filling in behind the kind for this album would be Dream Theater's Mike Portnoy, who The Rev considered a major influence. Utilising the last few remnants of recording the band had from Sullivan, they were able to feature his backing vocals on cuts Fiction and Save Me while most percussion and drum arrangements are also credited to him, in what ultimately, is both a semi-concept record about death and the loss of a close companion as well as a musical love letter to the New Wave Of British Heavy Metal (NWOBHM), complete with hair metal style riffage in worship to the likes of Judas Priest or Iron Maiden, whilst Queensryche's Operation: Mindcrime and Pink Floyd's The Wall were evidently drawn upon as blueprints for the project's narrative process.