Level with Orb of Storms/Stormblast Mine/Frost Bomb until Level 28 and then swap to Cremation + Armageddon Brand. Stick with Cremation + Armageddon Brand until level 55+ AND when you have access to Vaal Detonate Dead.
Gravicious unveil/craft on chest for 10% Life as Extra Maximum Energy Shield craft (important for ghost dance!).
Keep Vaal Detonate Dead at level 1 to reduce mana cost (only gains AoE with level so not worth levelling up).
Make sure your desecrate is levelled, you NEED a lvl 19 desecrate for 81 and below zones and a lvl 20 desecrate for anything beyond that or else your damage will be awful.
With changes made for 3.17, you only need to have 1 spectre now due to desecrate changes. Max spectre life is now 360% and every spectre above it will be scaled down to 360%, so the best end game spectres will be arena master as they will also buff you
More spectres listed in this pastebin link
https://pastebin.com/9JXQNrNL
---------------Extra tips---------------
The build works by casting desecrate and detonating the corpses that you spawn. To deal single target damage you need to detonate high life corpses which can be spawned using desecrate with high life spectres summoned (such as Arena Master).
To maximize single target we also have lots of ailment duration combined with carefully timed Vaal Detonate Dead usage to achieve large ignites that last 12+ seconds. Area + zone level will dictate your damage, you effectively
deal similar damage in a 68 zone as an 84 zone because the corpse life scales with zone level.
Focus Ailment Duration mod on helmet is EXTREMELY noticeable for longer lasting ignites, get this for endgame bossing.
Ungil's is used for proccing Elemental Overload (gives a lot of crit) but you can replace this by using a combination of the extra crit chance spell suppression mastery, crit enchant on boots and spell crit on weapon.
Main difference between necromancer, inquisitor and elementalist is as follows: Necromancer has a balance of defence and damage but lacks recovery, Inquisitor has defence and recovery but lacks damage, and
Elementalist lacks defence and recovery but has the most damage.
You can ditch the desecrate + spectre setup with an unearth setup instead but you need empower + enhance + alt quality phantasmal unearth in a +1/+2 gems item (such as Hands of the High Templar or Viridi's Veil)
and a +5 corpse unearth level enchant. The unearth setup avoided nerfs whereas spectres did not, so the unearth setup will be optimal.
---------------Gear---------------
All of your armour is basically just rares + life + spell suppression which can be crafted with essences / harvest spam until you get a good life roll and spell supression
Weapon is crafted with essences of fear until you hit fire dot multi and then you can multi mod
Corpse life is set to Herald of Kitava life as an Elementalist in T16 map: 138312
For Necro: 195942
For a base quality Unearth with level 90 Corpses (soft cap is 95) use: 103899
For Necro: 141191
For Phantasmal Unearth socketed into a +1 socketed gems item (gloves, boots, or helmet) with:
Level 2 Enhance and total gem level boosted to 25 (20/20 base, level 2 Empower +2 on weapon and/or amulet) with a +5 corpse level helmet enchant (level 90 corpse)
That's +16% Quality for 36% total. That's 72% increased corpse life. For this use: 166239
For Necro: 209530
Minmaxed Phantasmal Unearth in +5 Hands of the High Templar (Level 4 Enhance+Empower) and level 95 Corpses: approximately 336000
For Necro: 411,000
28% less damage with ignites has been added to the global mods in the configs to emulate the Ignite DPS nerf
