She can really do multiple ones or it’s just the lag?
Damn son… That’s new to me.
Sounds and looks reasonable to me that a boss can do that. If anything there should be more attacks happening.
I saw it did but not that many lasers. 
All of them actually deal damage, they aren’t visuals only.
She casted 4, than more 4, and more 4…
Phew…
Welp, I don’t remember it being that many when I fought her. But they were enough to make you keep moving until they were gone indeed.
UPDATE WITH VIDEO:
Might be lag, don’t remember her casting that densely 1st time I fought her (dc’d and had to start over), but it might be a HP-triggered thing, didn’t pay close enough attention to catch it if so. She pulled that 2nd time I fought her I think, and then after the battle I was too lagged to do anything.
Same thing happened to me, a lot tougher as a melee but I did it by getting her close to a rock and just wailing on her from on top of it.
Now we only need 20 more layers and we might have some bonna-fine bullethell.