AnonBackStabber.8536

I went through 80 stacks (20,000 essence) and received 8 exotic, and many hundreds of the rare backpack (w/ 920% MF). So I would expect about 1 every 10 stacks or so, maxing your MF... The droobert turn-in is about 8/5 better coin for the trash, but that would have taken me literally hours of mindless grinding (instead of about 15 minutes opening, plus another ~30 minutes maxing MF to 920% in Silverwastes[sW]). I still have another 120 stacks to go...