I made Greater Rift level 64 with my necromancer last night. It was with the Inarius set build. I think I have hit a limit as I tried GR65 twice and failed abysmally last night. I need a better weapon, presumably an ancient weapon and more damage for my necromancer if I want to progress further.

No more easy progress, now comes the hard work.

I also made progress with my Rathma set build. I hit GR55. The Rathma set build was unable to do GR60. The Pestilence set build is limited to GR50.

Inarius set build - GR64

Rathma set build - GR55

Pestilence set build - GR50

Tang'Oul set build - GR45