FWIW, my warriors have never prepped to that level. I don't think they've ever used shield or aura that didn't come from someone they killed, end even stoneskin isn't for every fight.

The flipside of that is, if I jump on a warrior and I can tell he has that kind of extreme damage reduction, I usually just run away immediately and try to raid/reraid/whatever again like ten ticks later. I'm not going to say I've never died to someone with that much DR, but I can't remember the last time I did.

Maybe you're more successful with the class than I am; it's not my best and I haven't paid enough attention to say either way.