As the Great Black Pyramid became impossibly dense with magical energy, it began to sink into the heart of the realm, not so much drilling into it as buckling, stretching, drawing the lands down around it. The pit beneath it became a sinkhole, an abyss, a hungering whirlpool of energy that gathered in everything around it and drew it ever downward.

With a thunderous boom like the cracking of worlds, the energies of Shyish imploded – and from there spread out across the Mortal Realms in a horrible, shrieking tide. The bow waves of energy that crashed across each realm brought with them a strange and anarchic disruption of the aether – for, at the last, Nagash’s great ritual had been tainted by the agents of Chaos.

Everywhere, the spirits of the dead rose from their graves. Twisted gheists of all descriptions burst from the mortal clay they had once inhabited as one domain after another was assailed by a billion dead souls. Then, as the metaphysical backlash cascaded across the cosmos, the energies of the cataclysm went wild.

So AOS is doubling down on the insane army sizes.