where to find living bomb mage rune (loch modan) - wow classic SOD

it is a semi-rare drop from the stonedigger troggs in loch modan, the same ones you kill for the in the defense of the kings land quest chain. it dropped for me after about 15 troggs, partway into the second quest. it seems to drop from any of the troggs here based on a few other mages who got it.