Khadgar's Essays on Dimensional Convergence

Khadgar's Essays on Dimensional Converence drops from the following bog beasts in the Swamp of Sorrows:
 * Tangled Horror
 * Swampwalker Elder
 * Mire Lord
 * Molt Thorn
 * Swampwalker

As a quest objective

 * Mazen's Behest (2)