Baldur's Gate: Dark Alliance II Hints for XBox
The first spells you want to max out in the necromancer are: animate dead, enervation, and anything that can get you faster energy rejuvination.
The main weapon would be two crossbows (fine or higher; anything regulation or lower has no magical value). Put jacinth and aquamarine in one for the living and diamond and pearl in the other for undead. I would know. I've beaten the game.