Board Thread:Warhammer 40k General Discussion/@comment-46.162.84.254-20130704080553/@comment-9676764-20140714185539

I think it said somewhere (I don't know where, so I may be wrong) that the tyranids were emerging from a lot of places at once, which may mean they've eaten quite a few galaxies around us.

I don't think necrons and tyranids would fight each other much, as I don't think tomb worlds have as much bio-mass than anywhere else, so the tyranids may simply do for tastier targets. Again I may be wrong.