Liche Priests and Liche High Priests are treated as Wizards but they don't generate any Power dice. They generate Dispel dice as normal in the enemy Magic phase - one per Priest and two per High Priest.

They always know all four Incantations.

A Priest can cast one of the four Incantations in each of his own Magic phases. A High Priest can cast two (or even the same incantation twice).

The incantation chosen is automatically cast like a bound spell, at a Power Level that is determined by rolling 2D6 in the case of a Priest's incantation, and 3D6 in the case of a High Priest. Note that these are not Power dice, and can neither be negated by enemy items, nor stolen or anything similar. Also, Liche Priests cannot take advantage of gaining additional magical power from such things as an enemy Miscast. Items which modify the Power Level of spell rolls do affect Incantations (such as the High Elf spell Drain Magic, or the magic item, Amulet of the Purifying Flame)

The rules for Irresistible Force and Miscasts do not apply to Incantations, but the rules for automatic failure do apply to Dispel attempts made in the enemy Magic phase. Also, the spell is always cast unless dispelled by the enemy For example, even if a roll of 3 or less is made for the Power Level. In all other respects the Incantations are treated as normal spells. For example, if the spell is destroyed by an enemy magic item (such as the Seal of Destruction from the Empire Magic Items list), then the Liche Priest who suffers the effect will not know that incantation for the remainder of the battle.