The Mortis Engine is a floating reliquary of death magic borne into battle by the soulblight-gravelords. At its heart hovers a shrivelled Corpsemaster, an ancient vampire bound to a screaming altar of bone, crystal, and captive spirits that drifts above the battlefield on wings of necromantic power.
The Engine is a conduit for the raw energies of Shyish, the Realm of Death. It amplifies the necromantic spells of nearby wizards and can unleash a catastrophic pulse of desiccating magic, withering flesh from the living and reducing enemy ranks to dust and bone. Around it swirl the tormented souls of those it has already slain.
At the core of many a Mortis Engine sits the Reliquary of Nagash, an artefact steeped in the power of the Great Necromancer. So potent is the death magic it radiates that the Engine is as dangerous to careless allies as to foes, and only the strongest-willed undead lords dare command one into the heart of the fighting.