LoD Poison Scythe Necromancer Skills and Runes

Active Skills
Grim Scythe Cursed Scythe Death Nova Blight 1 Simulacrum Blood and Bone 2 Bone Spear Blighted Marrow 3 Blood Rush Potency 4 Bone Armor Dislocation
Passive Skills
Stand Alone Swift Harvesting Eternal Torment Spreading Malediction

The build begins runs by summoning Simulacrum; due to the rune Blood and Bone you will get two minions at your side, and you need to be diligent in their upkeep as a large part of your DPS relies on them (you do not need to worry about their duration however — Haunted Visions makes them last indefinitely). If you find it hard to keep track of them in the thick of a fight, simply check with a cast of a spender (i.e. Bone Spear) somewhere outside the cluster of monsters; if two more spears shoot in that direction, you are set.

Rotate between your poisonous skills at your discretion; you only goal is to stay at your maximum Nayr's Black Death stacks at all times. You can throw Bone Spear to draw monster attention, Death Nova Blight to reduce incoming damage, or Grim Scythe to restore Essence for Aquila Cuirass upkeep. Right as your Convention of Elements rotation finishes the Physical cycle and reaches Poison, you want to pop Bone Armor to trigger the stun of Dislocation, which will maximize your Krysbin's Sentence damage bonuses during your burst cycle. After that, simply swing Grim Scythe Cursed Scythe alongside your Simulacrums and enjoy the devastation; once the Poison cycle is over, you can resume the rotation of Nayr upkeep and drawing monster attention into big packs for the next cycle of mayhem.

A major skill slot will be devoted to Simulacrum, one of the Necromancer's longest cooldowns — thankfully, with the power of the revised Haunted Visions, now made permanent minions at your side. You will be taking the "double summon" rune Blood and Bone, since you want to maximize the mimicking of your own skills.

You will be using a primary skill that will both stack Nayr's Black Death and also bring the signature poisonous devastation of this build. Grim Scythe Cursed Scythe is one of the most utility-loaded skills in the Necromancer arsenal. By default, it has a chance to apply the base effect of all three curses — Decrepify, Leech and Frailty — without the need to slot them on your bar. This primary gets boosted further by the worn Trag'Oul's Corroded Fang, ensuring the curse application and amplifying damage against affected targets. When you factor in the Simulacrums spamming this skill alongside you, it pushes the build to endgame potential.

You will also be using a duo of Essence spenders — Bone Spear Blighted Marrow and Death Nova Blight — again, simply for their Poison stack for Nayr's Black Death. As such, only use them to refresh the duration of the Nayr buff — their damage and utility is too limited to matter.

In a LoD build, Bone Armor simply acts as a damage reduction buffer, easily maximized in densely packed rifts. The more important half of the skill comes from the chosen rune, Dislocation — its 2-second stun will provide a moment of respite in the thick of battle, as well as an additional source of Nayr's Black Death, Krysbin's Sentence and Ancient Parthan Defenders (in the group version of the build) procs.

Swift Harvesting is the most logical addition to a primary attack-focused build, increasing the Attack Speed of both Grim Scythe and Siphon Blood with an impressive 15% bonus.

Since this spec falls into the category of low summoning builds, you can make use of the Stand Alone passive and its massive Armor bonuses with minimal losses.

Two interconnected passives — Eternal Torment and Spreading Malediction — will work off each other, with the former making curses applied by Cursed Scythe last indefinitely, and the latter — increasing your damage for each afflicted enemy with no apparent cap.