From the back of North American release edition
The Tome of Decay
Accept the Joyous Blessings of the Plaguefather!
Nurgle is the Chaos God of Death, Decay, and Rebirth. To those who accept his foul embrace, the Lord of Pestilence offers power over plagues, vermin, and even the inevitable grasp of entropy.
This book introduces putrid new Heretic Archetypes, as well as vile weapons and rules for Daemonic Possession, for forging Daemon Engines, and even for undergoing the grand apotheosis to Daemonhood.
This tome also includes rules for launching a Black Crusade, giving Heretics the chance to put the skills they have honed and the forces they have gathered in the Screaming Vortex to the ultimate test!
This volume contains descriptions of many of the blighted worlds of the Screaming Vortex, along with their depraved inhabitants! Trudging across the swampy realm of Mire, the Heretics can make their way into the very eye of the storm in the adventure The Heart of the Vortex!
Let nothing stop your inexorable stride to spread Nurgle's infectious gifts to all!
A copy of Black Crusade Core Rulebook is needed to use this supplement.
From the publisher's webpage:
Focusing on Nurgle, the Chaos God of pestilence and plague, The Tome of Decay, a supplement for Black Crusade, serves up all manner of ailments, resources, allies, and ideas for Nurgle’s grotesque followers. The Tome of Decay also includes advice for GMs on running their own plague-filled campaigns!
In addition to powerful new allies and ailments for the twisted followers of Nurgle, this volume contains many new resources for heretics of all sorts, whether they worship one of the Ruinous Powers or their own ambition. The Tome of Decay includes the Warpsmith and Veteran of the Long War Archetypes, whose endless war against the Imperium has sharpened them into peerless killers, and rules that allow Heretics to forge their own Daemon Engines or even bind Daemons within their own bodies to become powerful Possessed champions of Chaos. Finally, this Tome contains the rules for ascension to Daemonhood and running one’s own Black Crusade, allowing the most powerful Heretics to take the fight against the servants of the False Emperor to terrible new heights.