The Plagueburst Crawler is the Death Guard's engine of the siege made manifest, a hulking, daemon-possessed tank that grinds forward on rusted tracks behind a great ram-blade. Its origin lies in spite. It is said the Daemon Primarch Mortarion himself refined its design, sealing himself away for long months in the Black Manse upon the Plague Planet, labouring obsessively to craft a mobile gun that would outdo any wrought by the artisans of the Imperium.
Its principal weapon is the plagueburst mortar, which arcs its shells high over walls and ramparts to fall among sheltering defenders. Where these rounds burst they release not only high explosive but roiling clouds of daemonic spores, a corrosive miasma that eats through ceramite, flesh and rockcrete with equal ease, so that even those who survive the blast are dissolved by the contagion that follows. Entropy cannons and rothail volley guns bristle from its flanks to shred any armour or infantry that draw too close.
For all its lethality the Crawler is monstrously hard to destroy. Thick plates of corroded armour, a bloated daemonic hull and the malignant spirit bound within it shrug off punishment that would gut a lesser machine. Slow, patient and all but unstoppable, it lurches toward its target like the advance of a terminal disease, and in its shadow the Plague Marines make their inexorable assault.