Level 95 Hybrid Summon Holy Relic of Conviction Necromancer^3.27

Notes

You can start using Holy Relic of Conviction once you get the transfigured gem from lab or trade and optimally Lancing Steel of Spraying (which is also a transfigured gem) in order to trigger the Novas as much as possible. This requires a sword or axe to use
(with attack speed being the most important property) so you should start identifying weapons once you acquire one of the gems or start finding some valuable currency while levelling. You only need Resolute Technique for Holy Relic so as long as you keep using 
Absolution you don't have to allocate it.

Commander of Darkness can be replaced with Bone Barrier once you have allocated Indomitable Army and have capped Elemental Resistances (without CoD). 

The Minion Attack and Cast Speed crafted modifier on the Graceful Sword can be replaced with a Trigger (to automate Bone Offering) or Hit's can be evaded modifier (allows for the reallocation of the passive points needed to reach Resolute Technique). 
The modifier doesn't increase the damage done by the Holy Relics but instead allows you (via Spiritual Command) and the other minions to attack more rapidly for increased life gain/faster application of Withered stacks. However that's lost once you switch to another 
weapon in the low budget since those can't have crafted modifiers since they are unique items.

For the low budget version you can always use Severed in Sleep for Envy first, followed by United in Dream once you can afford it. Dendrobate provides a "free" Chance to poison gem and even as a 5-l is thus preferable over a 6l-corrupted body armour 
in the league start setup (replace Chance to poison Support with Void Manipulation if you get Dendrobate, independent of the number of links). Additional chance to poison for minions can be accessed via Ghastly Eye Jewels and amplified by 
Darkness Enthroned if necessary (requires additional resistances elsewhere).

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 later add a Pale Seraphim which you can find by playing maps with Beyond Demons or by interacting with 
Orichalcum Deposits (redo until you find one that spawns the Pale type of Beyond monsters, might take a couple of tries) and a Perfect Hulking Miscreation which can find in Rituals or buy from trade.

Amanamu's Gaze is a fine addition to the build but I didn't feel comfortable listing another costly unique and it's not as important as United in Dream or The Covenant.