Here my experience with Nemisis Assasine:
Me Assasine scorpion blade, I jumped in at lvl 120 boss one-shot me, no chance. I collect all 120 charms and do 2-3 lvl more -> same it oneshots me no chance
-> doing almost all 125 charms still same
-> have all 125 charms and lvl 130 no chance still one-shot me
-> finally on lvl 135 with some of 130 charms and all other under 130 lvl charms I got her
After that I went riftwalker 3 and it feeled like it was very easy compared to the nemesis.
So my fazit:
it was the almost hardest uber I ever made, and I did sam laz and so on. So for me it seemed very strange that this 120 uber was far more difficult then the 130 ubers so I guess it's very very unbalanced. Also it's very annoying running so far to that area again and again after failing. Also nemisis spawn is not garuanteed was running me almost crazy. So sadly it was nice idea but doing this uber and get the upgrade was so low fun
and frustrating for me I hadn't had that since 2.0 Greetz
Edit what I forgot to say -> ofc I don't need the set anymore on lvl 135. Also I'm sure you need better gear then any set anyway to beat that uber so like other ppl here say I can't understand the point of it either. But here many feedback so I'm happy to look forward seeing that uber got fixed