Originally Posted by
Kisho
If you're getting one shot by certain abilities, I'm 100% positive you could've done something to prevent it: Guard, EB, Dampen Harm, Diffuse Magic, not letting the boss get so many stacks, didn't DPS it hard enough, whatever it may be. I highly doubt that low stamina would've been your issue. You even say that when you did gear for stamina, you still had the same one shotting issue, so that's not your solution.
I can't think of a specific boss that requires a certain level of stamina to survive. There's some bosses where getting a bit of extra HP helps, but all you'd do there is swap to a couple of stamina trinkets, maybe a couple of items that have stamina enchants instead of agi, that sort of thing. Nothing so drastic as a full re-gear to prioritise stamina.
Assuming you have the correct gear level (i.e. not undergeared), then getting extra stamina just isn't needed beyond maybe swapping to a couple stam trinkets. That's it. If you're having survivability issues, you're probably not using your active mitigation correctly. To be absolutely sure, we'd need combat logs to analyse.
This reply also works for Acidbaron, with added iteration that there's no real required stamina level for any boss. Just get the gear, and you'll get enough stamina.