The point of Last Stand on a double attack is that each hit of the double attack strikes for 180k. You have to have 10k remaining after the first hit. That means you either have to block it (shield block cooldown is good for every strike in the encounter except the second one, which you won't have the CD up for yet), get an absorb shield, or have a minimum of 190k HP without last stand (180k hit from the boss + 10k minimum left over). What Last Stand does is it puts you above that 190k mark so that even if you manage to not block the attack, you still don't get one shot.
Originally Posted by Tengenstein
Kathy, I said, "I'm lost" though I knew she was sleeping
I'm empty and aching and I don't know why
Counting the cars on the New Jersey Turnpike
They've all gone to look for America