Board Thread:Warhammer 40k General Discussion/@comment-7186329-20130329201743/@comment-6078851-20130420010009

if a pact could be struck with the necrons (or the necrons contrive to do this themselves) the tyranids could be lured to a particular system by baiting it with bio-mass - orks spring to mind due to the speed and numbers of their procreative cycle. tyranids are drawn to said system by the vast quantities of ork bio-mass goodness, the necrons then use the celestial orrery to detonate the system's star - bye bye lots of tyranids.

don't know how many times that ploy could be used before the hive mind catches on, and obviously when detonating a star care needs to be taken that the system in question is faaar away from well travelled space, but it could drastically thin tyranid numbers.