An alien mass of writhing, terrible life has emerged from the Void of the Stars to collide with the floating prison, unleashing even stranger foes into the God-Skull. As the Keepers of the prison and their monk allies fight the invaders, that ancient evil begins to plot its escape. Can the heroes intervene to both repel the alien invaders before they reach the world below and keep a terrible power imprisoned? Or will one or both threats tear the world apart in a campaign of conquest and revenge?