The Hierophant

The title of 'Hierophant' is bestowed upon the highest-ranking Liche Priest within an army. The Hierophant holds the crucial responsibility of awakening the Tomb King’s legions from their ancient slumber. Without their magical influence, the spirits of these warriors risk being dragged back to the Realm of Souls.

To designate a Hierophant within your army:

You must include at least one Liche Priest.
If your army comprises multiple Liche Priests, the Hierophant will be the one with the highest Level of Wizardry.
In case of a tie in Wizard Level among multiple models, you have the liberty to select the Hierophant when compiling your muster list. However, you must disclose this information to your opponent before deploying your army.
The significance of the Hierophant extends to the battlefield:

Upon the Hierophant's demise, the magical animus of the army begins to dissipate.
Immediately upon the Hierophant's removal from play as a casualty, all friendly units with the Nehekharan Undead special rule lose the Regeneration (X) special rule.
Furthermore:

At the end of the phase in which the Hierophant was eliminated and during each of your Start of Turn sub-phases for the rest of the game, all friendly units with the Nehekharan Undead special rule currently on the battlefield must undergo a Leadership test.
If this test is failed, the unit suffers a reduction in Wounds equal to the amount by which it failed the test.
For instance:
Suppose your army’s Hierophant is destroyed during your opponent’s Shooting phase. At the end of that phase, a unit of Skeleton Warriors (Ld 5) undergoes a Leadership test, rolling a 7 (failing the test by 2). Consequently, the unit immediately loses two Wounds. During your next Start of Turn sub-phase, the same unit undergoes another Leadership test, rolling a 6, resulting in the loss of one Wound.