Plague Sorcerer Robe  

 

This combine does work. I completed the quest today. However, the first time I tried the combine I used yellow recluse silks from the smaller recluses and the combine did not seem to work. So it is possible that you may need to loot the yellow recluse silks dropped off the Giant Yellow Recluses. The giant recluses seem to be pretty uncommon but they roam the area ouside of the mino caves.