btw...on nightfall,second stage,if you cross the bridge silently(mellee kills only and no alerts)you then get into the fork lift truck and drive it to the big gates,position the left side of the truck against the dead centre and tight against it,if you get it spot on...when you dismount,you will spawn on the other side of the locked gate and there will be NO enemies at all,you can then stroll to the finish.Friend and I completed the whole mission in under 6 minutes.(weekly challenge was any mission on legendary in under 12 minutes)success!!!!!!!First stage you just run past everything silently!!!!!