Capture a Dire ravager( -415, 32, 312 ) Copy/waypoint -415, 32, 312 in Loping Plains.
Place the Dire Ravager Muzzle you received in your charm slot, then use (activate) it on a Dire ravager. You can find Dire ravagers just outside the village on the northwest side.
Note: Dire Warg and Dire Wolf do not work for this quest.
Note: In spite of the quest text, you do not have to actually bring the Dire Ravager back to Wolfmaster Heinrich. Simply getting the muzzle on the animal seems to satisfy the quest. However, you do have to make it back to him without dying, because that will break the 'charm' that the muzzle casts on the wolf. If that happens, Heinrich will say something about you having some trouble, give you another muzzle and ask you to try again.