See Flesh tearers. they can field all Death Co i believe.... they have speical rules for htem.
to be honest they'r enot that bad. cuz they really can't DO anything but charge straight for you... it's kinda funny actually you can run circles around them shooting at them
Now i play DE and anything that ignores Armour saves ignores the "they shall know no pain " rule, so it doesn't bother me as my retinue chews them up and spits them out, but ya..
fun to play against!
(everythign is as long as your openminded)