Tray is the only one I know using it. Just know that he is making the most of a bad situation that will hopefully get fixed later today. Hydra actually does pretty good in higher level NM’s. From what I hear it is spawning as a monster that is the same level as the dungeon monsters.
Example video from Tray’s build. Firewall is very fatiguing. You’ll have to circle kite every cluster while filling the center with fire. I’d use a controller if you have one.