Well, there's already been a few units in other armies that have gotten a Predatory Fighters-like/lite rule with unmodified 6's causing 2 hits instead of just 1, so agreed, definitely in the realm of possibility as you said. I think cold-blooded could work too, but with all our units already having BR 10, it's a bit OP. But I suppose with there being so many units nowadays with bravery debuffing abilities/traits this isn't as OP as it would've been a while back. What I could see happening is this becoming a sub-faction trait for the coalesced Seraphon as they are alive again and are actually cold-blooded creatures...IDK if they'd dock 2 BR points for it though, or something like that.