The build uses normal Ball lightning with cast while channeling cyclone and Cast when stunned triggered Ball lightning of static and Ball lightning of orbiting among other things. The build is quite tanky for an assassin, with the Defiance of destiny amulet and bloodnotch immutable force combo tech for the stuns which is enough on it's own to clear maps as long as you get stunned. I'm showcasing it on a t7 cemetery with whisps, but can do t16 albeit slower and dies from time to time, depending on the mods on the map. The build has suppress cap, elemental ailment immunity, capped all resistances, Lighning coil for phys mitigation, along with the watcher's eye mod which grants another 10% phys taken as lightning. I'm using an annihilating light staff for the triple damage, which makes it hard to cap resistances and it is not mandatory, you can use a staff with cwc and more damage etc.

PoB: https://pobb.in/j3fQfi35SdWL

I know I'm bad at whisp hunting, I was in a hurry as well. The build can be better, but I don't have the time nor the resources to make it better for now. Let me know if you have any questions about the build.