So just to give people an idea of how strong crits are, I went and threw myself at some enemies to see exactly how much damage they do. Instead of talking about specific situations, I think it'll just be easier to look at the raw numbers and see what players have to do to survive them.
Here's General Pask:
Here's a Gazluk Trooper:
Pask's normal attack crits hit for 740, his rage crits for 1400.
Trooper's normal attack crits for 448, their rage crits for 1028
Infiltrator's normal attacks crit for 496, their rage crits for 920 (Plus 222 in poison).
So outside of percentage based mitigation, a player needs to have a combined total of health and armor equal to the crit+1 with at least half of that being health. That means to survive Pasks' rage crit you need to have at least 701 HP and 700 armor, for troopers you need to have at least 515 HP and 514 armor, and for Infiltrators you need to have 461 health and 460 armor (And then be ready for the poison).
Don't even bother considering flat damage mitigation, as you can see vs the trooper I had almost full armor, and all it did was reduce the damage by 16. That's a 1.56% damage reduction. Compare that to the 20% damage reduction you get from Meditation 39 and it's easy to see why every tank needs to be running it.
So now I'd like to ask the devs, are those numbers around where they should be? Those life/armor values are the absolute bare minimum to survive one single attack. If you consider a second attack, then depending on the mob you need to add another 125-300 HP and armor to survive two, depending on whether it crits or not. Otherwise you need to be healed for 125-300 HP and armor right after getting hit by a rage crit or you risk death.
Also, just in case if some smarty decides to point out that I was naked vs Pask and of course I should die, I would like to point out that unless if I had over 1725 armor AND full HP I would have died anyways because 700 of that damage is going towards my health even with armor.