The Necroquake was a cataclysmic shockwave of death magic that tore through every one of the Mortal Realms, reshaping the setting's recent history. It was unleashed when Nagash, the god of death, attempted his so-called Great Work: a colossal ritual centred on an inverted black pyramid in Shyish, the Realm of Death, intended to redirect the realm's magic and bind every soul in existence to his dominion.
The ritual was sabotaged by the skaven, whose meddling caused the gathering power to detonate rather than flow as intended. The resulting necroquake rippled outward through all reality. The dead stirred in their graves, spirits long at rest were ripped screaming into servitude, and legions of nighthaunt, chain-rattling ghost-processions bound to Nagash's will, poured forth to punish the living.
The disaster also transformed sorcery itself. Magic became wilder and more abundant, and spells could now take on independent, predatory life, roaming battlefields as so-called endless spells long after their casters had fallen. The wars ignited by the cataclysm, known as the Soul Wars, pitted Nagash's hosts against Sigmar's cities and the Stormcast Eternals in a struggle over the souls of the realms, and its aftershocks continue to shape events to this day.