First let me just say that I normally play in a group (T5). When I play solo, which is probably 25% of my playtime, I play T6. Not for the efficiency but for the challenge/fun. This is also the reason why I don't run unity + follower combo. I don't want to swap gear/skills out whenever I receive a party invite. Anyway, I digressed. Here's the build:
Frenzy - Maniac: After the patch, I started running a zero spender build. Maniac seemed like a natural choice since it boosts my EQ damage which is really my only damage source.
Leap - Death from Above: Death from Above always seemed like the best choice for me. The stuns provide extra mitigation and helps keep monsters inside the quakes
Threatening Shout - Grim Harvest: 20% damage reduction and charms the enemies (with Resonance). This is pretty much what keeps me alive in T6. Grim Harvest is the best choice IMO with Resonance. Casting TS in the middle of a pack gives me plenty of globes. And without bloodthirst, globes will be my main source of healing outside of Templar heals. Without Resonance I'd go for Demoralize for the taunt, but with Resonance the taunt is negated by the charm effect
Warcry - Impunity: In my early tests in T6, this was pretty much mandatory. It sucked losing sprint but this helps me survive a lot more and helps me clear faster.
EQ - Molten Fury: Standard choice for fire LeapQuake barbs
WoTB - Insanity: This skill slot is probably the wildcard. What I noticed is that when I die in T6, it's usually from getting trapped by jailer, frozen. I might change this soon. (Played with Slaughter for a bit bit went back to Insanity)
Ruthless - for extra damage. All enemies fall below 30% at some point.
Berserker Rage - Cause I'm alway angry.
Boon of Bul Kathos - Not too thrilled with this taking up a slot but I hate having WoTB down when I need it so the extra 30 secs uptime is welcome. I would use Weapons Master here as a second choice
Superstition - For the 20% elemental damage reduction (replaced by Weapons Master in the latest video)
Rampage - Replaced Superstition. I decided to go full blown offensive passives after getting a decent upgrade to my pants. (took Rampage over Weapons Master as suggested)
Some of the passives can be changed to Brawler and Rampage, but I prefer having passives that are always taking effect. Ruthless and Zerker Rage are useful to mobs and rift guardians. Weapons Master is also a good choice but TBH I'm not sure how much damage it gives me (having 52% crit chance)
Skull of Resonance - This item is great and is probably the only reason I can do T6. The charm effect last for 15 secs and the chance is high enough that it's almost always guaranteed to charm at least one of the elites. Rift guardians are unaffected by the charm but they can be dealt with some other ways. The trick to using this is to jump to as much enemies as you can and then cast TS. Use subsequent leaps to position yourself outside the clump of enemies and let them fight inside your quakes. In the videos, you'll notice that I'm not getting attacked most of the times, so the only real danger are the ground effects. Another awesome thing about this is if you charm a fire chain elite, the charmed elite will break the chain!
Aughilds Set - Extra 15% elite damage and mitigation? I'll take it
Chilanik's Chain - The 10 sec speed boost is very conenient
Haunt of Vaxo - I have a better rolled Ouroborous but I chose to use this for the clones. It's pretty glorious when the clones pull enemies into myquakes. Plus they also provide extra mitigation for me
Trago'oug coils - I use this to reset my WoTB CD whenever I can
Templar relic (all skills) - Templar heals are awesome and lets me use my potion only as a last resort
Ess of Johan - Put this on your templar. You won't regret it.
Azurewrath + Freeze of Deflection - Nothing stellar but any additional CC is welcome, especially on Rift Guardian fights
My stats w Impunity:
Resists (w Impunity): 972-1324
12 mins 28 mins run. First run I did this morning. After this I swapped some gems around, so my stats are a little different from what's stated above.
8 mins 31 secs run. Got a little help from a conduit pylon in the first level and a channeling pylon later, hence the faster clear time. This video highlights how I can leap in the middle of mobs and avoid damage while doing so.
T6 Rift with Party. Skip to the end for chaotic guardian fight. 2 Elites + 2 Champs + Rift Guardian.
6 mins 45 secs run. Finally a map with good density! I'm using an updated build here without Superstition and using Slaughter instead of Insanity. Had a few close calls but managed not to die. I could have cleared this in 4 mins if I picked up that Conduit pylon, but that isn't anything to be proud of :p Updated build here: http://us.battle.net/d3/en/calculator/barbarian#WXfkTP!ZXSY!ccbcYb
< 8 mins run. One of two I did this morning.
10 mins run. Using the trending, no spender, no generator variation.
I would say I'm averaging 10-15 mins in T6 rifts depending on density. Edit: It's been a while since I had rifts over 12 mins. So probably averaging 8-12 now. I'm going to start collecting data on my solo rift play for tracking purposes.
Biggest problems with this build are enemies who just keeps running away. Vaxo and Ess of Johan helps but they are too random. In terms of rift guardians, Rime and Ghom are really the only two that gives me trouble.