Reclaim Krasus's Compendium - Chapter 1, Krasus's Compendium - Chapter 2, and Krasus's Compendium - Chapter 3 from Kirin'Var Village's Town Square. Use Archmage Vargoth's Staff to contact the archmage once you have the chapters.
If you lose Archmage Vargoth's Staff, speak to Ravandwyr at Area 52 to receive a replacement.
This quest is the 5th step in a quest chain in Netherstorm that begins with  .
The Kirin Tor sent one other of Krasus's possessions with our expedition. It was his spellbook, called Krasus's Compendium. Containing all the spells he mastered, it lent us a much-needed advantage in the war.
Before Kael'thas and his forces laid siege to Kirin'Var, the compendium had been stolen from me by a rebellious apprentice intent on studying necromancy. The apprentice and his followers divided and studied the text in secret, locking themselves inside their houses in the southern part of town.
Have you brought the book?
<Archmage Vargoth's image seems to inspect the compendium.>
It's a little worse for the wear, but considering the treatment it's been through, it's a miracle all of it survived. Safeguard it, <name>. Without it, we stand little chance of being able to break the tower's ward.