After waaaaaay too many attempts I finally completed the the Barbarian Wastes Set Dungeon Mastery. I learned a lot over my attempts and did a lot of reading and watching of other's attempts.
Here are my tips and conclusions:
1) General Tips and Strategy
Go FULL Damage and cool down reduction as much as you can without sacrificing damage. I had 1.4 million sheet dmg unbuffed, 50% CC, 550 CHD, 45% CDR, and 33% increased physical.
DO NOT overuse Whirlwind. It will kill mobs you don't want to kill instead of using them Rends groups. Only engage with WW if you want to wipe the room. You do not want to use WW as a mobility skill unless you want to wipe the room. *important*
Play aggressively (I cannot emphasize this enough). Do not hesitate or take too much time setting up 10 mob rends. Zoom around the map, kill small packs/singles instantly with WW and Gangway up to protect yourself. Use Gangway on large packs to setup an optimized Wrenching Smash, then Rend and immediately WW to kill off the mobs or Gangway to try to double dip another 10-Rend from the room.
Gangway can be used both to enter a large pack safely OR push mobs into the "center" to clump them. Since a mob cannot damage you while being knocked back and you can keep Gangway up nearly 100% of the time, this is much safer than Furious Charge. If you are a charging master... go for it though. I tried both and instantly had improved results with Gangway.
Watch for mobs your WW doesn't kill. I failed twice with one mob up because WW barely didn't kill it and I didn't notice.
Also, develop a route and stick with it. You will start to notice patterns with mob positioning and quantities per attempt. This will help.
Rend - Ravage (for larger AOE)
WW - physical rune of your choice, but I stayed with Blood Funnel
Ground Stomp - Wrenching Smash
War Cry - Veteran's Warning
WotB - Insanity
Sprint - Gangway (this makes avoiding physical dmg MUCH easier as it's nearly impossible to be hit if its up)
Unforgiving, Animosity, Weapon Master, Boon of Bul-Kathos. The theme is max resource regen and max uptime of WotB.
I wore Chilank's Chain, Reapers Wraps, CDR+CHC+CHD rings, and Bul-Kathos's set. I cubed Furnace (to help take down elites faster), Leoric's Crown (for more CDR), and Obsidian Ring of the Zodiac for more effective CDR.
Full rubies in armor, Diamond in helm. LvL 71 Bane of the Trapped, LvL63 Bane of the Powerful, LvL 70 Bane of the Stricken. Again the idea was to take down the "elites" ASAP as waller is one of the few things that can most commonly screw up a run.
Credit goes to Empyrian for this video detailing the use of Gangway.
My cdr was lacking even with obsidian , but it was okay since I ran Battle Rage-Ferocity instead of WoTB and Ground Stomp only takes a few seconds to reset. 1m sheet damage but with +39% fire and +26% whirlwind, so kill speed was still manageable. The more difficult part for me was the timing needed to navigate the trapped lanes, and to deal with larger monsters/elites. Sometimes they are near a rend group so it becomes necessary to either avoid their melee range or stun them as part of the group, or simply take them out first even if means losing the rend group. I also found it necessary to clear the first open area and first two lanes thoroughly, so there is no need to backtrack beyond the last two lanes for stragglers.
Basically, this dungeon is not terribly time strict but has a higher requirement for precise controls (similar to Earth set).