That is said to be one of the hardest fights on legendary. but all u gotta do is us ur plasma rifle charge up shot then while that is flyin towards them switch to your battle rifle and one shot from ur battle rifle and ne elite is down. and i find that the best place for cover is one of the most left boxes right when u enter that section. just charge up ur pistiol go out of cover launch it go back to cover to swtich to rifle and then come out just enough to head shot em. good luck i hope this helps cause this is exactly how i did it. O and of course a few good generade placements help 2
.