This is a build for [Nekros] that uses Blood Altar.
Blood Altar is the helminth subsumable [Garuda] skill.

Not only does it heal you, it also heals companions, other players and objectives (excluding defense mission objectives).
Most importantly, it heals your SHADOWS. That is why range is prioritized and duration is foregone.

One Umbra forma and one regular forma is added on from the polarity set-up of config B.

Combos

1. Blood Altar -> Heavy Melee -> Shadows of the Dead (total energy cost: 232.5)

2. Blood Altar -> Heavy Melee -> Terrify -> Shadows of the Dead (total energy cost: 348.75)

3. Blood Altar -> Heavy Melee -> Terrify -> Shadows of the Dead -> Heavy Melee -> Blood Altar x2 (total energy cost: 503.75)

Notes:
-Assumes the use of melee weapons that force procs with Heavy Melee attacks (eg. Scythes)
-It is best to use skills after the Heavy Melee Attack to benefit from Growing Power
-If [Growing Power] is active (even with minimum time limit left) when you activate Shadows of the Dead, the benefit will be there for the entire duration of Shadows of the Dead
-The above fact is true for both Terrify and Blood Altar as well

Core Mods

Shield of Shadows - maximum damage reduction is 90%, of which 89.88% can be achieved at 214% ability strength (this build gets 219% ability strength)

Despoil - whether it be farming or tanking Nekros build, this mod is a must

Growing Power & Blind Rage & Umbral Intensify - mitigate the ability power reduction from Overextended while maintaining the 90% damage reduction from Shield of Shadows

Overextended - the pitiful heal range of Blood Altar becomes formidable with this mod; the difference between this and Stretch is significant

Equilibrium - have companions equip Synth Fiber to pick up health orbs even at full health; Desecrate drops a lot of health orbs

(Primed) Flow - allows the use of other abilities after using Shadows of the Dead
([Nekros Prime] max energy at lv 30: 188) (Shadows of the Dead energy cost with Blind Rage: 155)

Arcane Suggestions

In General - in this build, arcane choices are highly flexible; Arcane Energize and Guardian are just suggestions

Arcane Energize - in the highest level missions (eg. Steel Path) enemies don't die fast enough for constant energy gain (especially effective with Energy Generator Dethcube)

Arcane Guardian - replaces [Health Conversion], opening up a mod slot while maintaining the tankiness

Weapon Suggestions

In General - Nekros Desecrate benefits from Slash and Cold damage types, since they cut/shatter corpses into multiple pieces which all get Desecrated separately

Primary - No suggestion

Secondary -
Pyrana Prime/Augur Pact to compensate for the lack of Brief Respite

Melee -
Reaper Prime/Scythes or other weapons that forces slash procs on heavy attack, making it easier to activate Growing Power

Companion -
Prisma Burst Laser/Augur Pact here instead of Secondary is better
Non-Sentinels/Link Armor works with Arcane Guardian and Health Conversion
All Companions/[Synth Fiber] for Equilibrium synergy

Substitutions

Cunning Drift - anything of preference

Equilibrium - defensive mods such as Health Conversion, Adaptation or Rolling Guard; maxed Arcane Energize should be enough as an energy source

Growing Power - can be substituted by [Power Drift] for another aura mod, but [Shield Of Shadows] will be 5% ability power shy of maximum damage reduction.

More Configs

Config A (Blood Altar, Umbra Forma)

Config B (Blood Altar, No Umbra Forma)

Config C (Petrify, Farm)

Thank you for reading!