Libram of Rumination

With some work you can turn in the Libram of Rumination to Mathredis Firestar to receive a Lesser Arcanum of Rumination, which will permanently add 150 mana to a leg or head slot item.

Required materials

 * 1x Libram of Rumination
 * 1x Black Diamond
 * 1x Gizzard Gum
 * 1x Black Blood of the Tormented
 * 30 gold

Source
Drops off level 50 and above humanoids.