The tablet tells much.  But not enough!  Not nearly enough!$B$BThere is a book, a digest that Yagyin wrote in ages past.  The... people I fled from... they keep this book in many places.  And their most learned study it.  It holds vast knowledge.  Knowledge to protect us!$B$BGo to Keeper Bel'dugur in the Undercity of Lordaeron.  Show him this sigil and he'll think you one of them.  Ask him for Yagin's Digest...and bring it to me!