Location: Westronbolt Gorge, it’s located south of the Malevolent Crucible which located on this area too.
I do this quest after meeting with Mayvin at Lohgrin, I am pretty sure that the merchant was not there before, however the Goblin Lord is already on this area, even before you meet with Mayvin. Speak to the merchant at the Westronbolt Gorge. He will tell you that a mutant hellion has eaten the iris gem. Now go to the location of the Goblin Lord to fight it.
Recommended Level: 50-55
Recommended time frame: After meeting with Mayvin at Lohgrin
Property: Therian, Armored
The battle is easy, however if you still have a trouble, then armatize with Mikleo and then use the Azure assault (strong against armored).