The world of Medusa V was already dying when the armies came. Massive warp storms had engulfed the planet, heralding its inevitable consumption by the Immaterium, and the Imperium ordered a desperate evacuation of its billions. But the death-throes of a world are a beacon to the predators of the galaxy, and to Medusa V they came in droves.
The Fall of Medusa V became a churning maelstrom of war as faction after faction descended upon the doomed planet. The Chaos Space Marines sought to hasten its plunge into the warp, while Orks, Necrons, Tau and the swarms of the Tyranids each pursued their own dark purposes amid the collapsing cities and storm-wracked skies. The Astra Militarum fought only to hold the evacuation lines long enough for the transports to fill.
As the warp storms reached their apocalyptic climax, the very fabric of reality unravelled. Those who could flee fled; those who lingered were lost forever as Medusa V was drawn screaming into the immaterial abyss. Whatever prize the myriad invaders had sought, none claimed it. The planet simply ceased to be, another world erased from the star-charts, its fate a grim footnote in the ceaseless attrition of the 41st Millennium.