Whilst within 12" of a Casket of Souls, friendly Liche Priests may apply a +1 modifier to any Casting roll they make. Additionally, any model (friend or foe) that casts a Bound spell whilst within 12" of a Casket of Souls may apply a +1 modifier to the Casting roll.

Note, however, that this bonus does not apply to any Bound spells cast by a Casket of Souls.