great video, and even better resource for newer players. I showed this to my little brother, who is in grade school, and after a few tries he was able to knock this out easy.
I found that in the beginning of the saber encounter, specifically for me, if I’m able to hit saber with helion and arcane needle using necrotic grip as soon as he comes out of the ground, the DOT from that seems to cause him to stay instead of briefly disappearing.