The NECROMANTIC MAGIC
is the best magic deck by far. Not only is the spells the best, but the sorcerer may pick which spells he want and he may recast them.
THE CURSE OF YEARS
One of the best offensive spells in the game. Kills one third of a unit instantly. There are several ways to use this spell well. The first, and the best, is to cast it on a powerful elite unit with tons of characters. There is no "look out sir" rule, so every character has to test. If you are lucky you kills a general and a whole army runs when the Crown of Command is lost. The second way is to cast it on a big archer unit far away from the general, and hope it will flee. The third is to cast it on anything else except war machines and small units.
THE WIND OF DEATH
Another destructive spell. Wonderful against Orcs'n'Goblins, Skaven ( so many units to thrash), Empire and Dwarfs(so many war machines and archers to thrash). Try to target artillery and missile guys which is placed on a line and is not expected to move around very much. Thus, you might be lucky and thrash something, or the enemies will just move away, reducing the accurancy of their shots.
THE HAND OF DUST
This is the bane of Bloodthirster and anything less (that would be pretty much in fact). Give it to your Vampire Lord (or count) and charge some big, nasty and ugly enemies before finishing them off in the magic phase.
Remember the Wights and Wraiths, especialy the terror causing Wraith could be useful.
THE GAZE OF NAGASH
The Bane of every cavalry unit in the game becouse of the "no armour saves allowed" pharagraph. Give it to your Vampire general, as he often will be at the front of the army.
DRAIN LIFE
A useful spell for your Necromancer if he doesnt have the amber amulet since it restores his health. Also, a S3 hit with no armour saves can be really destructive against all T3- opponents.
THE DARK MIST
One of the spells I usually would avoid, but it can be effective in combination with the Sword of Destruction, the Black Gem of Gnar and more. The Cloak of Mists and Shadow is better, since it is impossible to dispel, and you may pick another spell instead.
VANHELS DANCE MACABRE
Very useful indeed, especialy against archer or knight based armies. Youll have to be smart and think of the following movements when playing against Bretonnia for instance, and to avoid their charges, Vanhels Dance is great. Against Skaven, Orcs'n'Goblins and Lizardmen, you wont need this spell at all,
SUMMON SKELETONS, RAISE THE DEAD & SUMMON UNDEAD HORDE
Of these, Summon Skeletons is the best. Give it to your Necromancer Lord, and cast it if you have some remaining power cards. At the other side, you'll only be able to create a new unit one third of the times, but it's seldom needed since your skeleton units cannot be broken.