Whilst Arkhan the Black has the Liber Mortis his Wizard Level is increased to 5. If the Liber Mortis is ever destroyed, Arkhan the Black immediately loses a Wizard Level, and therefore must lose a randomly determined spell.
Source: Warhammer Fantasy: 8th Edition
Whilst Arkhan the Black has the Liber Mortis his Wizard Level is increased to 5. If the Liber Mortis is ever destroyed, Arkhan the Black immediately loses a Wizard Level, and therefore must lose a randomly determined spell.