Hello,
his spell has a hitbox that in my opinion needs to be improved because although I ran counterclockwise without any difficulty (I have 50% movement speed) I taked damage (not too much, I have a lot of resistances), although I was close to the beam but not on it.
There is also the common issue which I already mentioned in another post, allows me to move the boss.
Unfortunately I moved him outskirts of the arena during his “Voidic Whirlwind” spell and unintentionally I was not being able to attack him or to use any of my abilites.
Have a nice day