I run a similar build as Ump but I like to equip Enfeeble to make sure I get a condition.
1. Bone Fiends-real damage dealers and good meat shields
2. Bone Horros-cheaper meat shield
3. Verata's Sacrifice
4. Healing Spring-Heals 45 every 2 seconds for 10 seconds 225 heal area
5. Enfeeble-I use this on the grasps and it really seems to help keep minions alive
6. Virulence-8 down arrows on 1 and 4 down any nearby plus weakens them
7. Blood of the Master, Winnowing, pet, troll ungent kind of a free for all
8. Rez signet
I also have been so sick of rangers not interrupting meteor showers and siege attacks that I equipped a bow and took barrage, I know it's silly but it does pretty good damage anyways plus it's fun to do something before the first enemy or pet falls. I take distracting shot to at least get 1 interrupt on a dryder or wurm. By doing this tho I had no way to heal myself since I put 10 into marksmanship and took taste of death for emergencies. Of course I'm running a N/R and the N/Mo Virulence build sounds more suitable for your build. As he was saying it's nice to have an order necro bring heal area, but you can't count on it. I also run a super soul reaping in tombs for the extra 2 energy per kill, I've found that what kills me with 470 life will kill me with 400 life 1 second later

Enfeeble and Virulence combined with a 5 good barrages makes for about 30 maintained minions until the first nuke that is. Oh and the disiease doesn't transfer to your minions for a whole line of reasons.