SHORT GUIDE:

Basiacally like any other [Nekros] build

1. Cast desecrate and keep it on for a maximum of loot for the cost of 10 hp per kill.

2. After killing 7+ enemies, find a secured spot and cast shadows of the dead for damage reduction and distracting the fire away from you.
   Try to keep the spawned enteties alive, by recasting the ability, since each Shadow of the Dead reduces your damage taken. Recasting from scratch makes you vurnerable for being damaged for much longer, so try to keep them alive.

With another forma in the aura slot, it's possible to replace [Steel Charge] with [Growing Power], in order to increase the damage reduction gained from Shield of Shadows, but Steel Charge offers that little higher damage output - chose as you like, but don't forget to bring a weapon with a fair status chance in order to maintain the +25% power strength, if you run [Growing Power]

Arcanes are optional too.

Arcane Energize gives a source of energy of the constant recasting of Shadows of the Dead, which is otherwise not giving due to neutral efficiency. If you don't own Arcane Energize or simply don't want to use it, you should consider replacing [Stretch] with [Equilibrium], in order to maintain a high energy pool. If that's not an option as well another one would be the mod [Streamline] on the same spot plus using the Zenurik focus school with a maxed energizing dash, which brings you to a lower casting cost, plus an extra five energy a second.

Arcane Strike provides a faster attack speed, which is helpful, since high level missions usually focus around the use of melee weapons.

Another good option for increasing your survivability is running Arcane [Guardian], which gives you another good damage reduction through the use of addiotional armor.