Your army must include at least one Wizard to be the army's Hierophant. If your army includes several Wizards, this will be the one with the highest Wizard Level. If two or more models have the highest Wizard Level, choose which of them will be the Hierophant. Remember to tell your opponent which one is the Hierophant at the start of the battle. The Hierophant must use the Lore of Nehekhara.
The Hierophant uses his powers to bind the souls of the dead to the mortal realm and restore the bodies of fallen warriors. The Hierophant, and all models in the same unit, have the Regeneration (6+) special rule.
If the Hierophant is destroyed, the magical animus of the army starts to dissipate. At the end of the phase in which the Hierophant is removed as a casualty, and at the start of every friendly turn thereafter, all friendly Undead units (except characters) on the battlefield must take a Leadership test. If the test is failed, the unit immediately suffers a number of Wounds equal to the amount by which it failed the Leadership test, with no saves of any kind allowed. These Wounds are distributed as if from a shooting attack.
If, at the start of any of your turns following the death of the Hierophant, there is one or more friendly Wizard Characters on the table who know spells from the Lore of Nehekhara, then one of these models may be designated the new Hierophant by passing a Leadership test. If passed, he becomes the new Hierophant following all the normal rules, and no unit in the army needs to take the Leadership test to avoid losing Wounds while he remains alive.