Trag'Oul Death Nova Necromancer Skills and Runes

Active Skills
Siphon Blood No rune chosen Death Nova Blood Nova 1 Bone Armor Dislocation 2 Frailty Aura of Frailty 3 Blood Rush No rune chosen 4 Simulacrum Blood and Bone
Passive Skills
Spreading Malediction Stand Alone Swift Harvesting Final Service

Start the run by activating Frailty and tracking the Trag'Oul 4-piece set bonus stack, going up to 300%. Once Trag'Oul is maxed out it is time to summon your Simulacrums, which are buffed by the stacked set bonus. Then, activate Bone Armor — cast in range of an early pack of (ideally lower threat) monsters to maximize its damage reduction bonuses, capped at 30% for 10 affected monsters. Once the damage reduction is in place, you only need to activate Bone Armor when you're about to burst monsters down in your nuke cycle, since the Dislocation stun will proc the worn Krysbin's Sentence for the full damage bonus benefit.

Once you have a good pull of monsters, channel Siphon Blood to trigger the Funerary Pick damage bonuses, and keep track of the Convention of Elements elemental cycles. On Physical, pop Bone Armor to Stun and proc Krysbin's, and resume the Siphon Blood channeling, which will self-cast Death Novas from the powers of Iron Rose. Make note of the Simulacrum positioning and make sure they are in range of your primary targets (ideally Elites), since the Simulacrum damage greatly outclasses your own! Once a pull thins out, move on — even if some valuable enemies are left at low health.

Your damage hinges on the Bloodtide Blade, which scales off the number of enemies you fight simultaneously. Try to drag the low health targets to the next fight, or abandon them altogether — you will fare much better if you simply form the next big pull. Otherwise, use the time between Physical CoE cycles to maneuver from fight to fight, kiting enemies and pulling them into the next big fight. Jump into Oculus Ring procs with Blood Rush whenever possible as you prepare for your burst cycles, since this is another damage multiplier to stack on top of your own.

The focal point of the build is Death Nova, whose damage you will amplify through various means — elemental damage on gear (see this build's gear page for more information), the interaction between Funerary Pick and Siphon Blood, and skill-specific items like Bloodtide Blade and Iron Rose. The latter is especially important, since it practically locks you into the health-spending Blood Nova rune. You can easily mitigate rune's blood cost however, and even gain superb damage amplification bonuses from Siphon Blood Power Shift and its interaction with Funerary Pick. Due to the Trag'Oul 2-piece set bonus, you also gain all the other runes of Siphon Blood (hence the unruned suggestion above) — the health globe convenience of Blood Sucker, the crowd control of Suppress, the Essence boost of Purity of Essence, and the increased healing from Drain Life.

Bone Armor brings some much needed damage reduction to the build, stacking up to 30% when you hit 10 monsters upon activation. It is recommended that you take the rune Dislocation for an extra on-demand proc of Krysbin's Sentence from the 2-second stun.

Simulacrum will be taken with the rune Blood and Bone in order to greatly multiply your damage output, as both clones will duplicate your Blood Novas, and — unlike your Iron Rose procs — their casts will do trigger Area Damage. These minions will be made permanent (rather than the fleeting duration they have by default) with the worn Haunted Visions amulet.

Mobility cooldowns are a GR pushing staple inclusion, and Necromancer's solitary tool for the job — Blood Rush — is even better in a Trag'Oul setup, where you attain all the runes at ones via the set 2-piece bonus. You gain another utility-laden cooldown with the toughness of Potency, health restoration of Transfusion, extra Corpse from Molting, and doubled charges of Metabolism — all at a removed blood cost due to Hemostasis.

Lastly, you will be taking a Curse into the build to improve your overall damage output. For AoE convenience, it is recommended that you take an automatically applying rune such as Frailty Aura of Frailty, whose radius mimics the caster-centric Blood Novas. Note the rune's synergy with Pickup Radius on gear, and try to obtain it in the Secondary Stats of your items.

Since this falls into the category of low summoning builds, you can make great use of the Stand Alone passive and its massive Armor bonuses.

Spreading Malediction increasing your damage for each enemy afflicted by Frailty, with with no apparent cap — incentivizing you to make as big of a pull as your Toughness can handle.

Swift Harvesting is a straightforward addition to the build, as you inflict all of your damage through Iron Rose's Blood Nova procs via Siphon Blood, and this passive amplifies the latter's attack speed by a significant margin.

Lastly, Final Service provides you with a cheat death proc and a safety net against bursty elite affixes.