A Death Guard force is largely made up of Plague Marines, and still follows the doctrines that their Primarch Mortarion taught them. Their tactics are based on the use of foot-slogging infantry, and the hardy use of their Bolters. Any vehicles that were in possession of the Death Guard at the time of the Horus Heresy have since fallen into disrepair, or have been commandeered by cheeky Nurglings.

The Death Guard make full use of Nurgle's gifts, spreading turmoil, advancing solidly amidst a mist of choking disease, surrounded by Nurglings at their feet and summoning horrific Plaguebearers from the Warp. In larger battles where the outcome is of dire importance, a decaying Daemon Prince may take the reigns of the army, or a Great Unclean One may posses a Champion.

The Death Guard often organizes squads by multiples of seven, based on the sacred number of Nurgle.

Originally the Death Guard believed that humans should be free of oppression and that hardship should be faced with faith in inner strength, strong will and stern resolution. During the Heresy, these beliefs were twisted into contempt for the weak and the conviction that individuals were not fit to judge for themselves what was best for them.

When the Legion was trapped and infected by Nurgle in the warp, their arrogance and contempt for weakness turned against them. Their surrender to Nurgle caused them to become self loathing and now they seek to spread ruin and decay in order to let their own fate appear less shameful in comparison.