Rift Quest:Treacherous Transmogrification  

This only works on Goblin Bombsmiths, which are always accompanied by a Fire Elemental. The goblin becomes a Befuddled Treant! Seems the Goblins here are actually Treants that have been Transmogrified by the Fire Elementals.

Easy Mode: Cast the Goblin Transmogrifier and switch targets to the Elemental, as the Befuddled Treant will attack him. IF you can manage not being too close when the Elemental dies the Treant will not even chase you, and about 7 seconds later he will vanish. You could also just use the Goblin Transmogrifier and walk away while they argue about it.