WWW Build?
If you’re looking for a Rabid condition build, you can obtain most Rabid Exotics from temples with Karma and from WvW with badges. Exotics are good enough in WvW, although Ascended and buffs sure does put a stat difference there.
The terrormancer still works, but for damage, 30/20/0/0/20 is a pretty popular and effective build.
Look for posts from Rennoko, he showcase videos of Condi necro in WvW with Rabid, Dire and Celestial gear. That will give you a good example of what you can and can’t do.
If you want to zerg though, conditions aren’t always best there, peoples will melt before your conditions can even take effect, or will be removed too quickly with mass condi removal.
Before investing heavily in a spec, make sure it will fit with your WvW playstyle.
Panhauramix Guardian/Pistoleros Engineer/ Orbite Thief
Gates of Madness – Leader of Homicide Volontaire [HV]
Genuinely it costs about 60g to get full exotic gear [Including weapons and trinkets].
Luckily you can cut the losses by more than half with Karma and Badges of Honor.
In WvW there’s these armor and weaponsmithes that will sell you exotics for a few badges + a bit of gold.
Also, after temples in Orr there’s these Karma vendors who sell a full exotic set + trinkets for 42k Karma EACH piece, stats depending on the temple you’ve completed [Check the wiki for full list]
Good luck
Violette Glory [Warrior]
Bala Rama [Herald]
Since you’ve mentioned the your main purpose is zerging, it’s fair to warn you that conditions and terror builds aren’t very effective. Conditions are cleansed too quickly for them to do any real damage and fear requires two traits to maximize making it very expensive to build around.
When zerging, there are two basic necro builds. The first is the 30/10/0/0/30 glass cannon build. The forum is littered with them. They dish out ungodly amounts of damage at range but offer little in the way of support or survivability. If you like seeing big numbers and don’t mind going down once in a while, this might be for you.
The other type is the power wellomancer. This is typified by Ascii’s build: good power, crit chance and damage around 50% and lots of armor (knight’s is key). This build can frontline with the big boys and Plague can be used to great effect to help facilitate tough pushes. It is, however, betrayed by its weapons. Without cleaving, this necro’s power doesn’t dish out widespread damage making it more inefficient than a true melee class.
So, it really depends. Pick a play style and customize the basic build theory to fit the way you want to play. Necros have quite a bit of flexibility.