This has to be done in VETERAN mode.
Tl;dr: Wait with killing a shade to escape until the very, very last second before getting oneshot. Wait until they are standing still. You can see this at 00:25 min in the video linked below. This is stressy, you have to stand still for very long, and this is very dangerous in later fight phases with all the overlapping AoEs. So the easiest method is skipping this mechanic in later phases.
You can also do it apparently by never, ever playing the shade mechanic, but you need very good dps for that, because you need to get her to 10% of her health before the very first shades kill you.
I recorded an audio commentary to better explain what I do here. Have mercy, English is not my first language. And I am really, REALLY sorry about the Discord sounds, I forgot to set myself to "Do not disturb"-mode before the fight.
Note: You can also use skills such as Sorcerer Streak, Dragonknight [Dragon Leap], Nightblade Ambush and Shadow Image to teleport out of the middle without killing any of the shades.
