Not sure how useful this is since his loot quality obviously varies and since he is on specific layouts for Halls of Agony 3, but here goes. A few of the layouts for Halls of Agony 3 have a row of furnaces that Inferno Zombies come out of with a Resplendent chest in front of the middle one. Upon looting the chest Garrach the Afflicted(Purple named) says something about stealing his treasure and emerges from the iron maiden next to the pillar. If you use your town portal as he starts to come out and then return, the iron maiden will still be intact and Garrach will be there waiting to be killed. After killing him he will reemerge from the iron maiden a 2nd time to be killed again and be looted.
long story short.
1. Get an Act 1 Halls of Agony 3 map with the resplendent chest and Garrach the afflicted.
2. Loot the chest and use your town portal.
3. Return and kill Garrach for loot.
4. Kill the 2nd Garrach that comes out of the iron maiden for additional easy loot.
If its useless, disregard. If its a repost, my apologies. If you get anything out of it, enjoy.