I’ve played to level 50 so far with a build roughly resembling this:
http://www.gw2builds.org/create/bwe_1/necromancer#3.2.1.0-1.9.11.20.2-20.20.0.0.0-6.10.3.6
I’ve been focusing on +condition damage and power for my gear stats, with a slighter weight on vitality and precision.
I don’t use any pets at all, the build can take out packs of 4-6 mobs in PVE, I’ve been pretty happy with it thus far.
I open with the scepter, run in Grasping Dead, then Well of Corruption, switch to death shroud and AOE drain, pop out, go to plague form, spam plague until end, if anything is still alive, you should be able to pop into shroud again and AOE drain once more. In PvE I drop the Plague Signet and use my owl that stacks bleeds (I think it’s a Norn ability)
For PvP I use Axe/Warhorn and Staff and just spam marks and switch to axe if I get someone in my face.
The End.