In the grim dark future of the Warhammer 40K galaxy there is only war. The Hive Fleet Leviathan was only the tip of a very large iceberg, it turns out Leviathan was only a scouting party for the full force of the Tyranid swarm. The Tyranids infestation crashes through the galaxy like a wave, consuming everything in it's wake until there is nothing left but teeming hordes of bugs. But something else dwells in the darkness.
The Star God known as the Deceiver sees this huge influx of life in to the galaxy and sizes the opportunity, he uses all his considerable might and awakens the Necron Dynasties in there entirety and gives them a single purpose.
So in the battle between the unrelenting force of the Tyranids Vs the immoveable object of the Necrons who is the victor?