MedievalCraft-Mod:Class Book - Assassin
This book will show you all your class levels, as well as reducing your Assassin level by 5.
This book looks just like the Big Book except for it is named differently. Place in your toolbar and select it and then right click and it will show all your levels of your classes and reduce the Assassin class by 5.
This is Crafted By Placing the "Big Book" in the crafting slot, and keep grabbing each class book and crafting that one in the crafting slots until you get to Assassin.