I've looked and looked, and I can't figure out how Va Dyn Kar does the power drain. I stood there auto attacking, just watching the debuffs, screenshots and all. And they all talk about crushing damage and CB/Pot debuffs, and the spectral one has one hit of many damage types. None of them say "power damage" or "power drain." The only thing that's possible is the Clinging Shadow, which still says in the text that it's a curse, though now it seems to be a removable arcane status. That says, curse must be cured to avoid destruction. What's destruction? Is that the power drain?
Ok so when you see the emote "crush, crush, crush" and rocks start falling from the sky, if you get hit the rocks you get massive power drain. As soon as you see him say that text just back up and let him come to you. Or be like me and stay around him but try to guess/Dodge the rocks hah
When he says that, he also does the kick-up thing, usually by the time I land, I"ve already been hit with a rock. Too much happening at once for a simple solo I think.