I can confirm that pestilence doesn't work from scratch even if you go halfway melee with a scythe for bosses. After level 110 it gets harder as you can't farm the farming ubers without dying. Technically, you could get to 115, but dying so often in cows isn't fun. And Torajan jungles seems impossible because of the mana drain, the regular stun novas and lots of ranged attacks overall, even if you only walk instead of run.
Lazy sorc could work, but I don't think the damage is enough, looking at how the nova charge damage on my tempest sorc is nearly negliable. Plus, she doesn't have a lot of defense, so going into melee range could pose a huge threat.
Something that could work a lot better imho is a pestilence unholy paladin. You get Vessels on top of that buff that attacks in an AoE, free -enemy resist, lots of movement speed from superbeast, liferegen, speeds, defense, DR, PR, SD... basically everything you need. Maybe that build can get to and farm kurast better than the pestilence necromancer can. Only detriment is the lack of the passive malice damage buff and the fact that you need to craft a paladin spear first.