Wells - aoe dmg, aoe heal, aoe protection xD Nice balance between dps/support/survive. Probably best necro build for dungeon runs, also not so bad in WvW.
I use on my necro celestial gear, but also can work Valkyrie or Combination of Celestial+Berserk/Assassin.
Build is mainly for staff, for brutal aoe annihilation of enemies. Other weapon set is up to you, axe/warhorn or dagger/dagger-warhorn should be nice =)