i have been working this dungon on heroic difficulty with prot pal and 4 rets (item lvl445ish) so i can learn the fights. No healer needed so far, the flash heals and hand of protector is more than enough healing for heroic. I just wanted to post a few thing in case other boxers are wondering.First. you can do it on heroic to get the essence ( visions of perfection ) which is still the best in slot for most specs..you can get the rank1 and the recipe for rank2 of the last boss ( two runs ) also on heroic, you have a small chance to get the sprockets needed for rank3..but this seems time consuming.. im going to start working on mythic now and use heroic as filler if i dont have a mythic+ key. The sprockets can now drop off junk yard last boss and king. some have reported that the higher mythic+ you do, you can get up to 4 total. (thats all you need to get rank3 )