Duronn the Runewrought can be found at the Terrace of the Makers in the Storm Peaks. [44.9, 38.1]
Objective of Edit
Duronn has an ability called 'Reconstruction' that heals him to full health. You can use the Oathbound Warder's Earth Shock ability to interrupt casts of this ability.
Other methods of interrupting the casting (fearing, etc) also work.