I just blew through this entire place. I didnt see anything custom in there, other than perhaps the mobs, etc. No custom drops as far as I can tell (there was some guy wanting slivers of granite, those take you to an empty zone in some sewers somewhere).
The mobs themselves drop gold. The preceeding zone, everything dropped 10x the amount these mobs do.
The riddler thats supposed to spawn at the end (I think) definitely wasnt there.
Am I missing something here? So far it just seems like the mobs were re-tuned to be level specific, and that was about it.