A Death Company dreadnought is a variant of the standard Imperial dreadnought walker used by the Orders of the Adeptus Astartes. Dreadnoughts are cybernetic walkers that house the mortal remains of a fallen Space Marine hero so that he may continue to fight for the Emperor and his Chapter, even after his body has been mortally crippled. Death Company Dreadnoughts are used exclusively by the Blood Angels Chapter and its many successor Chapters.
Death Company dreadnoughts differ from standard Imperial dreadnoughts in that their occupants are Astartes who suffer from the Blood Angels genetic defect known as their Black Rage. The Black Rage is a genetic flaw that causes mental instability as a result of the psychic imprint left in the Blood Angels Legion's gene-seed by the death of their Primarch Sanguinius.
This flaw was first discovered during the Battle of Signus Prime when Sanguinius was crushed and suffered a horrific wound at the hands of the Bloodthirster Greater Daemon Ka'Bandha. The condition is largely incurable and few Blood Angels have managed to defeat this so-called "gene curse".
When a Space Marine is overwhelmed by the Black Rage, they will be reborn into a world of constant anger, hatred and blind rage that cannot be contained and will result in the slaughter of all who stand in the way of the rampaging Astartes. whether they are friends or foes. In addition to the memories of Sanguinius, the Blood Angels and their kin are genetically endowed with a small portion of their Primarch's unearthly power, increasing their strength and vitality to superhuman levels.
Rather than face a slow, insane death, the Blood Angels and their successor Chapters will reform these battle-brothers, recently slain by the Black Rage, into a special unit of the Chapter known as the Death Company. The dreadnoughts of these Chapters are not immune to the Black Rage, and a dreadnought pilot consumed by the Black Rage may also join the ranks of his Chapter's Death Company. A dreadnought under the influence of the Black Rage is nearly impossible to control or tame, and as such can spiral out of control for sunny days until the Order's Techmarines can manipulate a device to disable it.
The Order's Sanguinary Priests can then decide whether the dreadnought's Astartes occupant should be sedated until the next battle, or stripped of his life for another to take his place. If the dreadnought chassis occupant is still healthy enough to follow the instructions, he will be transferred to the Order's Death Company, where his dreadnought body will be able to withstand enormous punishment and his unending rage will cause the deaths of many enemies will face its own annihilation.
Many successor Chapters to the Blood Angels that use Death Company dreadnoughts deploy them into battle with dreadnought launch pods that launch the war machine straight into the heart of the enemy battle line, allowing the dreadnought's unstoppable might to be harnessed for maximum effect.