The Prophet-Singer is the leader of the Acanti and caretaker of the soul of the entire race. The previous Prophet Singer was infected by the slaver virus which attacks the higher reasoning centers and slowly starts to destroy it's conscious mind and self awareness thus making it easier for the Brood to control him. Normally when the Acanti die, they hurl themselves into the heart of a star. In the case of the Prophet-Singer, this is essential because if it is not consumed by a star then the Acanti racial soul it carries cannot be released and passed on to its succesor. When the Prophet-Singer died, the Brood grounded it in their third world and turned his rotting corpse into their throne city. The combine effort of the X-Men, the Starjammers and Binary were able to defeat the Brood and release the Acanti soul which was passed on to the new Prophet-Singer.