Mix it with either two shields - 1) Demonbreaker or 2) Monsterclaw.
Buff your intelligence considerally high (at lvl 51 my INT is 85 and Luck at 45). If you have Tokens to pay for a good Dark weapon go for Nightslayer (3-4000 tokens) - 8 to 30 dam , 15% to hit, can summon a Night terror to attack from above. If you don't have tokens go for Bonethrill Staff - 4-21 dam, 5% to hit, can summon a dark ghost to attack.
If you still have alot of tokens buy "Little Death" as pet as it do 6-60 dam Dark dam and Dark Splatter Spell. If you can't afford it choose "Bag of Bone Spell" which are availble at your local Necromancer and for pet "Dark Vampragon"
The reason why I found Necromancer to one of the best character is because of the special ability of Undead Giant which makes your skelton to inflict 5 times damage to the cost of 30 MP without you have to invest stats point in STR and DEX and still gives ALOT of Melee dam plus you are a master in Magic (and not to forget the ûber cool robe). The necromancer have one of the best Summon creature of all character (alot of Dark dam), perhaps only surpasses by the Vampire Slayer's summoned Vampragon.

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Another things is the great Defense a necromancer have with the combination of the shields I talked about. A Lvl 10 necromancer on a lvl 51 character look like this:

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A personal preference: While playing Necromancer play some music from "Tool" or "Cradle of Filth"
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