This is not easy achievement to get. Not the hardest or the most time consuming but difficult indeed, even more for someone in my timezone as it's very hard to find players good enough AND committed for a no-death run. And even so, along the way, there several chances for an RNG death (Harvester trash pack, Flesh Abomination exploding hoarvors...)
However, today, right now, I finally managed to be grouped with good players, committed to do the no-death run, everyone focused in not dying stupidly believing that this achievement doesn't require us to stay alive the whole time, including the final boss.
In fact, I'm 100% sure that a a few weeks/months ago the achievement description explicitly said that it would not count the Lord Warden fight. Mechanics in there still bugged, sometimes the second portal doesn't appear or they overlap each other and count as one (among other things).
And this not announced change (I'm with all patch notes since 2.3.5 opened) made me miss the opportunity I'm trying for MONTHS.
C'mon, ZOS!
I am the very model of a scientist Salarian, I've studied species Turian, Asari, and Batarian.
I'm quite good at genetics (as a subset of biology) because I am an expert (which I know is a tautology).
My xenoscience studies range from urban to agrarian, I am the very model of a Scientist Salarian.