Necro farming

My first post ok i am having alot of trouble with trying to fuguire out a nice mass area dmg farming build for my necro! I can switch my secondary to any class now so thats not a problem currently i am N/R!

I once saw a monk do some amazing dmg to mass foes at once and had all the griffons on the run dead in under 30secs or so. I want to go for something of that effect, but i have a thinking block lol can anyone help thks!!!!

go n/mo and use smiting skills

Here. I'll post my build for you. I dont think it will work for farming, but it does a lot of damage, and Offering of Blood lets me use the first 6 skills one after another, basically.

N/Mo 20
Attributes
Blood Magic: 16 (Superior Rune, + Ragged Head Scar)
Soul Reaping: 10 (Minor Rune)
Smiting Prayers: 9

Skills
Awaken the Blood (Boosts Blood Magic and Curses up by 2, so Blood is at level 18)
Shadow Strike
Vampiric Gaze
Vampiric Touch
Balthazars Aura
Unholy Feast
Blood Ritual (I have this here for team play, so you can put whatever you like, spamming Life Siphon would go nicely here)
Offering of Blood [E] (This skill is a complete must. At the moment without AtB, it gives 21 Energy to me, which I need to be able to cash out Balthazars Aura and Unholy Feast)

Basically, just use the skills in that exact order, using Offering of Blood whenever you need it. If you need any more help, please whisper me in-game ^^