A codex for a faction of Heretic Astartes dedicated to Nurgle called Death Guard, for use in Warhammer 40,000 eight edition.

From the webpage:
Within this 104-page hardback, you’ll find:

BACKGROUND:

• The Wages of Heresy
• The organisation of the Death Guard
• The Chronicle of Virulence
• Heraldry and colour schemes for a variety of vectoriums and warbands
• Background and details on each character and unit available to a Death Guard army
• A showcase of beautifully painted Citadel miniatures,

RULES:
Everything you need to get a Death Guard army primed for games of Warhammer 40,000 is in here:

• 33 datasheets containing rules for every Death Guard unit;
• Army abilities reflecting the Death Guard’s methods of war;
• Gifts of the Plague God: wargear both ranged and close-combat used by the Death Guard;
• Points values for all miniatures, weapons and wargear for use in Matched Play games;
• Scions of Mortarion: rules for Battle-forged armies:
• 6 unique Warlord Traits,
• 14 unique Stratagems (with a focus on the psychic might of this army),
• the Relics of Decay (6 rare artefacts unique to the Death Guard),
• the unique Contagion psychic discipline, available to all Death Guard psykers;
• 6 unique Tactical Objectives.