Hi together,
as i often read here and find useful things, I hope to have found something usefull for some:
On Nightmare Act I you have to be on quest "The Broken Blade"
If you enter one of both caves (possible on both! Warrior's Rest or Crypt Of Ancients) you have a save spot. So you can easily kill the golden mob there and most times receive some yellow things. Additionally its a few xp for this one and a chest is there too to loot.
After killing the golden mob, you just log out and in again and can do this again and again to get some nice xp and few good items.