Secondary professions for a Necromancer

Necromancers have some of the most powerful spells, with the longest recharge and highest energy cost.

Always remember, when choosing secondary skills, that native skills often have better synergy with the profession's purpose, interact better with the profession's other skills, and benefit from runes.

Necromancer Warrior
Necromancer and Warrior can work very well together. Although not a full warrior melee option, the combination of good weapon skills, close in Death spells like Vampiric Touch that ignore armour and range spells such as Deathly Swarm make this character a formidable team player. A MM option included makes this character extraordinarily difficult to take down and a valued contributor. Good necro skills and finesse are important. Best build would seem to be Death, Hammer and Soul reaping. It can be great fun.
 * Curses are a powerful ally to a Necromancer / Warrior. Use of the spells Barbs and Mark of Pain can decimate enemies quickly.

Necromancer Ranger

 * This profession combination provides little benefit for a Necromancer primary. Necromancer and Ranger skills have very little synergy.

Necromancer Monk

 * The 55hp solo Necromancer is a very effective farming tactic.
 * Minion Masters sometimes use Heal Area as minion maintenance with Blood of the Master, although this split can draw points from other necromancer attributes where it would be more useful.
 * A reusable resurrection skill is useful for any character in PvE.

Necromancer Mesmer

 * Echo and Arcane Echo can be used to increase the damage potential of some of the longer recharging necromancer skills.

Necromancer Elementalist

 * Glyph of Lesser Energy can be used for energy management.

Necromancer Assassin

 * Enduring Toxin and other Deadly Arts hexes combine well with Soul Barbs.
 * Signet of Toxic Shock and other deadly arts skills combines well with Toxic Chill.
 * The hex spell Barbs can be combined with daggers for extra attack power.

Necromancer Ritualist

 * A Necromancer spirit spammer rarely has to worry about running out of energy.
 * A Necromancer can function as a healer using Restoration Magic, managing energy with the Soul Reaping bonus.
 * A reusable resurrection skill is useful for any character in PvE.

Necromancer Paragon

 * A minion master can use "Fall Back!" to heal his army on the move and "Go for the Eyes!" to increase minion damage, however these are among the few shouts which affect minions.

Necromancer Dervish

 * Mystic Regeneration can combine with necromancer enchantments such as Dark Bond and Aura of the Lich, but this tactic is easily outpaced by Blood Renewal.