Secondary professions for a Necromancer

Necromancer Warrior
This profession combination provides little benefit for a Necromancer primary, however shields can provide extra armor, and Mark of Pain, Barbs and Flurry can be combined to increase damage.

Necromancer Ranger
Serpent's Quickness can accelerate slow recharging spells

Necromancer Elementalist
This profession combination provides little benefit for a Ranger primary.

Necromancer Mesmer
This combination has access to two effective energy-management attributes: Soul Reaping and Inspiration.

The mesmer skill Fragility spell along with several necromancer spells to cause conditions can be an effective spike or pressure technique.

Necromancer Monk
Healing Prayers can counteract sacrifices from skills like Order of Pain to enhance their damage output.

Soul Reaping is often used to fuel the more expensive healing or protection skills from the monk lines

Spoil Victor is a powerful elite for a 55 hp Necromancer

Necromancer Assassin
This profession combination provides little benefit for a Necromancer primary.

Necromancer Ritualist
A Necromancer spirit spammer rarely has to worry about running out of energy.

Necromancer teleports, unlike shadow stepping, allows one to carry bundles with them. A N/Rt can be a melee bomber by teleporting into a clump of foes and dropping an item.

Necromancer Paragon
Many Command skills can affect minions, and Leader's Comfort can be an effective self-heal without Leadership when surrounded by minions.

Necromancer Dervish
This profession combination provides little benefit for a Necromancer primary.