Ok, a HUGE concern people are having with combining necromancers is the scaling cost of using BotM on hordes of minions. There is an answer!
Aura of the Lich cuts your sacrifice to 1/4 of the normal - that will cut a deadly 120 health sacrifice down to a managable 30. It also gives a 253 point heal after 46 seconds, regardless if you refresh it every 20 - that means if you refresh it as soon as it recharges, you can have regular 253 point heals flowing in every ~20s. Use it!
Same with pairing it with Blood Renewal - typically I will have 9 Blood, for +5 regen and a 130 point heal after 10s. With a base life of 485, AotL reduced the 25% health sacrifice down to a mere 31, while I will regen 100 life and be healed 130 life - a net +199 life for 5 energy!
If I spam BotM on 10 minions I will similarly sacrifice just 31 life, and heal them all for 122 for just 5 energy. Even healing 20 minions (10 more from another necro), I can support the health sacrifice easily with the massive healing coming in from AotL and BR. Without AotL, that's asking for a swift death from massive health sacrifice!
Of course, the big vulnerability is enchantment stripping - if you get hit with Shatter Enchantment it will basically do no damage... if AotL is shattered you might take say 107 damage from the Shatter, but be healed 253 from AotL ending... no problem. The problem is that sacrifices will now crucify you until you can get AotL back up

If you had BR up as a cover enchant then you will take no damage from Shatter - a 107 point shatter will get reduced to 54 by AotL, but BR ending prematurely will heal you 130... sweet!
Another cover enchant could be Death Nova, which is cheap but otherwise quite useless
The other alternative is Dark Aura. This is nice in a way since all the sacrifice spamming will cause you to radiate AoE and scatter anything that tried to melee you (nice defensive ability), or you could deliberately Aura Bomb if you wanted... The bad side is that Dark Aura deals damage to you, so it can be an unwelcome health drain by itself.
I'm sure there are other / better cover enchants, so lets hear them
edit: oh yeah... Dark Bond
