New York City-based Horrorcore Rap duo The Flatlinerz drop their new album BLACK PLAGUE, featuring Frukwan, Gravediggaz, Shabazz the Disciple & School Of The Gifted, produced by Shaka Amazulu The 7th, via Black Stone of Mecca Records & marketed by Ground Zero Entertainment PDX Who started Horrorcore? Gravediggaz or The Flatlinerz? this is a debate…