Need help on a bomber build

[Hidden Prayers]

I've been trying to work out a build for my necromancer that I can use to generate large amounts of damage quickly. So I started experimenting with a N/A build that makes use of Dark Aura and Vampiric Spirit along with shadow arts to quickly move into an opponents zone and deal large amounts of damage.

Here's what I've some up with so far:

Attributes:
Blood Magic: 16 (12+3+1)
Death Magic: 10 (9+1)
Soul Reaping: 10 (9+1)

Skills:
Dark Pact
Jaundiced Gaze
Vampiric Spirit {E}
Dark Aura
Life Siphon
Return
Death's Charge
Consume Corpse

I use Revenant's Armor and a Milthuran's Staff.

I usually cast life siphon, dark aura, death's charge to my target, and then put on vampiric spirit. I follow that with jaundiced gaze and a spamming of dark pact. The problem that I'm finding is that I spend way too much energy. So much that I'm only able to use dark pact once or twice before i'm tapped.

Anyone have any suggestions for solving this issue, or other comments on the build. Thanks for the help!:D

Edit: This build is AB/FA oriented.

[Rancour]

Toss Vampiric Spirit away and go capture Cultist's Fervor. I lowers energy cost and gives you a sacrifice with every cast. Of course, you're going to have to change your Bread and Butter skill, Dark Pact, to something else or the sacrifice will be too hefty.
Another, more favorable, option would be to use Aura of the Lich (halves damage and cuts sacrifice by 75%) together with the Nightfall skill Blood of the Aggressor.
BotA has a measly 5% sacrifice, which is 1.25% with Aura of the Lich on. Not only that, but it also has a significant life steal of 40-something (good when your max hp is halved) and a very low energy cost. It recharges in 3 seconds, so a back-up spamming skill might be a good idea. I'm gonna test this build once Nightfall is out.

A note of advice: Don't use these builds in PvE. It's an awesome concept in my opinion, but because enemies run from you, you're less effective (perhaps the Assassin skill lines have something mass-crippling, hmm?). In PvP you can work if you overload an enemy monk with armor-ignoring damage, but it really isn't viable in PvE, in my experience.