I did it legit on one this week. "CHEESED" on two. The legit one, when entering valus arena, I hung back at the ramp with the shield. I hung out there till he rotated. Used the left side 'non psion side' to switch over. Used that large cube on the 2nd level as my cover and used mida to be sure no cabal snuck up from behind on me. Took a good long while but got it done. Trickiest part is when rockets mcdickface is in his free roam mode. Too much running around to consistently get hits on him.