Board Thread:Warhammer 40k General Discussion/@comment-14745711-20130906234048/@comment-6078851-20141206161634

in regards to tyranids affect on the warp: a couple of things to note first - the hive-mind is a singular entity, the accumulation of every single tyranid organism contributes to the hive-mind, so the more tyranids there are the larger/more powerful the hive-mind becomes - tyranids are the hive-mind and the hive-mind is tyranids. the hive-mind is "unfathomably intelligent" (codex-quote), but entirely alien. the vast, vast majority of tyranids are in a state of frozen hibernation awaiting their arrival in the milky way before they 'wake up'. the hive-mind is already very powerful but it's barely awake - as more tyranids awake from their slumber the hive-mind too awakens more.

so, tyranid psychic abilities are derived from themselves (i believe as a result of the scale of the hive-mind) and this manifests itself as 'the shadow in the warp'. this shadow has a sort of muffling effect on warp-based powers - as a hive-fleet approaches a star system all warp-communication is cut off and any warp-sensitive folks can only see/sense an approaching 'shadow in the warp' that fills them with a sense of dread.

that's effectively all that's really known about their effect on the warp but i believe that as the hive-mind continues to awaken the 'shadow' will grow too. given the sheer unimaginability of tyranid numbers i'm of the opinion that as the 'shadow' grows it could eventually become potent enough to actually have an affect on the gods themselves, and emps, muffling their abilities as well as muffling the abilities of everyone with warp-based powers.