I so relate with Sons of Horus, me and my friend in our more newbish days tried to pull so much crap XD only to later go "oh >.>; oops"
And with Rune/mantle it protects from instant death from things 2x the strength than your toughness, such things like forceweapons and some others dont kill by 2x the str, but just kill outright so rune/mantle do not protect
Its right there in the wargear discriptions saying that it protects from things would normally killing outright by 2x's the str
W L D
16 1 3
W L D
6 3 1