Level 95 Hybrid Raise Spectre Necromancer^3.28

Notes

Should be leveled as Absolution (skill gem/passive tree example). You can switch from Flesh Offering to Bone Offering as soon as you have allocated Mistress of Sacrifice.

Commander of Darkness can be replaced with Plaguebringer once you and your minions have capped Elemental Resistances (without CoD). 

For the spectres you can use the Stygian Silverback from The Riverways in Act 2 and the Host Chieftain from The Southern Forest in Act 6 for leveling. 

You can switch to the Spectre setup once you have access to the Frostbearer. The Forged Frostbearers can be found in maps where they might spawn after interacting with Verisium Outcrops, the Primal Crushclaw can be found in Harvests (blue crop). 
You can alternatively ask for them in the global channel 666.

You can replace Bone Chill with Feeding Frenzy in the mapping setup for aggressive minions. This also allows you to replace Feeding Frenzy with Minion Life for your utility Spectre. Costs you ~30% damage.

Imbued Gem Supports:
For the main spectre you can use any of the gems listed in the setup. 

For the utility spectre Culling Strike would be great. This allows you to replace the socketed gem with Minion Life for additional minion survivability.