A new lifetap would be super, or Splurt II (everyone wants this to happen, even mobs).
A spell line most necros don't use or necessarily want being updated is bad... Being a mana battery dubious... if thats the route being headed how about an update to/modification of Mind Wrack instead- more powerful (mo' mana) but with some kind of drawback (stun? group stun? recourse damages hps? your pet shoves an iksar up your nose?) to keep it balanced (or just mo' mana).
Seems to me the PbAoE Dot is highly situational and would be more suited as a "regular" spell instead of a runic/artifact- nobody wants to raid and raid and raid and raid to finally get some spell they'll cast 2/3 times ever.
Artifact = crazy big dot = sounds about right
<player hat>
As a high end raiding Necro I really look forward to the PB-AE, and I think most other high end raiding necros would be eager for it too. We have a level 29 AE of suck, and that is the only AE option we have. Numerous mechanics and situations exist in the raid game that would make having a PBAE very handy, no matter the mana cost.
Splurt as is, is still a very useful ability, that, rightly or wrongly, I still use in raids. I'd love to see it upgraded, <vague forshadowing hat>but maybe a new spell isn't the way to go about it...</vague forshadowing hat>. And at least from where I sit (having all my relics) I haven't used a normal lifetap in a long time. Life flows just work better.
Either of these however, I would like to see more than the essence transfer. It has uses yes... but please please please take away the mana component. Make it straight HP, or also give strength or charisma or something, but don't give necros and unlimited ability to give their mana to someone else. It will only end in tears for the class.
Personally everyone loves pets, and I'm forced to wonder if old Ludras is going to become more obsolete with the new MAG and BST pets previewed. Maybe a new sack of bones is in order?
</player hat>
<dev hat>
Honestly Necro's are a really strong class as is, you don't usually hear them complaining about very much. Drastically increasing a Necro's power is a bit too easy, and some of their abilities in the right circumstance (Harro Festering Curse!) are down right ridiculous. DPS increases are just not as likely to happen as utility increases.
I'll also pipe in that I really think of this new set Magicians are going to be very happy, and from the listed teasers, I think they are the strongest set as listed. Those are my personal views on it however, and don't represent the rest of the staff, nor does it hint that we aren't still tweaking them and others.
</dev hat>
<disco hat!>