A couple of suggestions on the most contentious build in the game.
The problem with the ult that I see is using it to clear out a dozen or more slaves at a time in a horde. The ult is great for elites, but ridiculous for hordes/ambients. Perhaps if the ability were only able to target bosses/specials/elites then it would remain top-tier whilst no longer being a crutch for cocky green circle chasers. It would also make it perfect for picking out an elite in a horde.
The beam in vt1 was great in that if you could keep the beam focused on a single enemy its damage output would grow. A moving ogre made this challenging. Currently the “meta” use of the beam staff is “the wiggle” which takes advantage of the instant tick with stagger. I think making the tick rate start much slower and increase in speed (opposite of current) would work rather well to make “the wiggle” unviable.