How do we defeat the Lich in Gauntlet dark legacy?

Right now me and are friend are both level 12s. One's a sorceress and one's an archer. In the level before us, it said "Only a fool would face the Lich without the Good Book." Well, we can't find any "Good Book" and we've attempted killing the Lich many times now without any book and have failed. What do we need to do in order to get this book or defeat the Lich? Thanks!