SMOGmonkey said:
-Use grenades
-If you don't have grenades, find some in the room
-Throw those explosive/gas barrels at him
-Run around, hide when he starts throwing grenades at you
-Don't stay in one place too long
-He is slow and loses sight of you easily
I most definitely caught hell w/ this too OP, so honestly don't feel bad. When I when into this fight most of my augs went into the social & hacking things--I had a few sparse prax pts thrown into some strength augs, but nothing major--so this fight was a helluva battle for me too. But I'm thankful that I had at least some passable weapon mods & pretty good amount of grenades.
.....and let me tell you, those grenades are seriously your golden ticket to kicking this bastard's ass.
I tried many times (and deaths) w/ the whole trying to throw the barrels & canisters crap but frankly that sucked for me b/c of endless supply bullets...and headshooting him? Pfft, don't even hardly if at all play any FPS type games so that's not really my forte and didn't work as effectively either (though did do somewhat better using my machine pistol in terms of blind-firing is his ass a bit).
But strangely enough after over several hours (and countless deaths) w/ asshat--the quickest way I actually got him? A couple of shots (more by accident then a deliberate plan, lol) and 3 grenades--all frag ones....he went down in less than 5 minutes (to my deliriously stupid surprise!!). No lie.
The first one I hit him w/ was actually just escape plan method I came up w/ for when I went in that first weapon room on the side--as I always seem to have that mofo trap me in there (as I'm getting some much need supplies). So my plan was really to use the frag grenade to disorient him long enough so that I could slip past him and get to the other from (in far side of the 'fight' area). Now THIS room would probably be of big use to you as it is the one that has not only 1 frag grenade but also an EMP one as well. I heard EMP one does a helluva good job on him b/c when it hits it really blows the hell out of his currents of whatever and I think he stays stunned & disoriented far longer. Of course as irony would have it I actually got him down before I even had to use it (as I was keep the EMP grenade as the last resort/finisher).
The second frag grenade I got him w/ I actually happen to toss it near one of those red barrels--so I'm sure that added damage as well, plus sprinkling maybe like 2 shots around to his head--and last one (which I actually did think it would BE the last one) I caught him near a one of the columns....which not what I think about, I wonder if there was a fire extinguisher hanger there which is sped up me killing him?
As SMOGmonkey mentioned, the key (it honest to god took me some time to get down) is to keep moving & duck out of his sight when you can. If you've built even remotely on stealth then make that an advantage for you b/c he seriously is stupid as hell, lol. I didn't my best work at him when he lost sight of me.
But above all else...don't give up!! I know that sounds corny as hell but really don't do it. I was at a breaking point too, but w/ some persistence, craftiness, and hell even some luck, lol, you CAN be him.