Any hope for this old build?

Hi everyone.
I tapped out somewhere around 3.20 and recently came back to play a bit with my old char - Blade Vortex Assassin (Standard). I know there's been a fair number of changes (probably all nerfs), especially with Withering Step and Elusive. I want to salvage the build into something workable without having to completely switch and refarm everything. It seems to be doing fine enough in T16s that aren't hyper-juiced, but it struggles badly with special bosses (guardians, conquerors, incarnations etc., haven't even tried any Elder/Shaper runs).

I've never been an expert on theorycrafting and doing a deep dive for this will probably just discourage me entirely, which is why I'm humbly asking for any advice, tip, direction you can give me on how to improve this - survivability, single-target damage, probably passives that changed over the years and no longer make sense here.

If it's impossible to do anything meaningful with it, then an advice on an alternate Shadow build that "feels" similar to this would also be appreciated.
Thanks for the help in advance and cheers in the new year.

https://pobb.in/G1x3xhGRZikB