They do with termie armor, but fluff wise it makes sense... And invuiln save is basically a form of warp energy... With their mind as open and risked to the warp, it would take a powerful relic (the shard of the emperors armor in the crux terminatus) to ward off harm.
__________________  "Truth is infinite. It is defined by our perception of the facts; therefore we can never know absolute truth, we can only guess at it. A man who knows he has done no wrong needs no redemption, regardless of the views of others. The truth is what he believes it to be. A man who knows he has done wrong can only be redeemed when he chooses to forgive himself."
-Lord Inquisitor Balkoth
Black Saints Adeptus Astartes Chapter |