Played 2 years ago but not the way I was supposed to. Now I’ve been schooled by my friends who played D3 on PC when it came out and I’m doing builds, etc. Stuck on T11 and can’t get past GR 54 solo. Using Necro Inarius Bone Armor build at Paragon lvl 453. Only missing Compass Rose for my build. Any advice on how to advance further would be welcome. 
I only play Demon Hunters these days, so I’ve kind of lost touch with other builds. I also play on a PC, so I don’t know the differences from PS4.
But, I would suggest looking at this build on Icy Veins and see if it helps:
Necromancer Generator Build with Grace of Inarius
I’m sure there’s other guides out there as well. Like on DiabloFans.
Good luck! 