Good grief, no kidding. Even when he goes into Frenzy/glitch mode at the end, which is supposed to make Vex horribly inaccurate (I'm assuming because their heads are no longer attached), he gets brutal with those headseeking bursts. It's not uncommon to lose 2 members of the team during that stage, and taking cover behind the stairs/pillars doesn't really work because he'll charge on over - I'll pick off the Harpies so we can at least move around the map, it's about the only time I ever run Nightstalker just for invis rezzes. (Also, FFS, does NO ONE know how to run crowd control anymore? If 30 enemies spawn on the battlefield during an intense battle, don't run away from them and get shot in the back, SHOOT them! Grr...)