Necron motivations

• Shield of Baal [Word of the Silent King]:

"The Tyranids are anethema to all life, and life is what the necrons require for supreme domination. So, too then, is the primal destiny of the Devourer incompaitible with our own."

• Shield of Baal [Devourer]:

"The tyranids were a threat to the necrons. They were life unferrered, anarchic, predictable only in their insatiable hunger. Their consumption of the lesser races proved problematic in the establishment of necron dynastic rule and eventual goal of the imposition of lifeless order against a galaxy teeming with Chaos."