The Laws of Undeath All models in the Vampire Counts book (except Ghouls and Bat Swarms which are Alive!) are Undead and have the following special rules:
THE GENERAL
The army must include at least one Wizard who will be the army's General.
If the General is destroyed, at the end of the phase when the General is killed and at the beginning of every Undead turn thereafter all Undead units on the battlefield must take a Leadership test. If the test is failed, the unit suffers a number of wounds equal to the number they failed the Leadership test by. No saves of any kind are allowed against such wounds.
Note that Characters never suffer wounds because of a destroyed General and units can use the Leadership value of a character leading the unit for this test, as normal.
Ridden Winged Nightmares and Zombie Dragons do have to take this test, but can use their rider's Leadership value.
BREAK TESTS
Undead cannot be broken. Undead units beaten in combat suffer one wound for every point they lost the combat by (no saves allowed).
BATTLE STANDARD
Undead within 12" of their Battle Standard suffer one less wound when defeated in combat.
IMMUNE TO PSYCHOLOGY
Undead are Immune to Psychology.
CHARGE REACTIONS
Undead can only react by holding their ground.
MARCHING
Undead cannot march move unless they are characters or are within 12" of their General at the start of their Movement phase.
CAUSE FEAR
Undead cause fear.