Okay, it's obvious we need one of these. I don't have the patience to put everything I'd want to in here in one go, so consider it a WIP.
Q: What exactly is the HotA build?
A: This is too complicated to answer without a post of its own. (See below) I also highly suggest watching some or all of the videos linked to, especially if you'd rather skip reading the details.
Q: I'm a DTWW barb, can I use HotA?
A: Chances are you can get by fine with your current build and gear. There are several variations of WW/HotA hybrid builds which work very effectively. The simplest way to work it in is to replace either war cry or OP:KS with it, and leave a fury generator. Simply use HotA against rare elites, goblins, and pesky kiting elites and leave your playstyle unchanged otherwise. If you're accustomed to running without a fury generator, you can use hybrids using OP:KS or Rend which are covered in the following post.
Q: What type of gear works best with HotA? Do I have to use a Skorn?
A: Being able to stand in the thick of things and HotA mobs down without the movement that's typical of DTWW requires high defenses. Stack resistances and HP as heavily as you can within your budget. It will give you much more build flexibility. As far as weapons go, HotA alternates damage between the mainhand and offhand, so low-DPS stat sticks that are typical for DTWW are undesirable. The higher the damage of both of your weapons, the better. Skorn is a popular choice because it gives you tremendous damage without having to worry about balancing damage ranges. It is by no means necessary. Dual-wield setups can be at least as powerful if done correctly. Critical hit chance is especially important, and to a higher degree than it is with DTWW. Critical hit damage is also very important as a properly built HotA barb will be landing crits close to 100% of the time.
Guide continued after the page break..
Some posts on dual wield versus Skorn later in the thread:
Q: How much HotA resource cost reduction do I need, if any?
A: The answer to this depends heavily on the build you choose. The consensus amongst most experienced HotA barbs is that none is necessary if you use a build that incorporates a fury generator such as bash or frenzy, and plenty argue that reduction makes keeping WotB harder. On the same token, if you want to use a build without a fury generator, such as a WW/HotA hybrid, I would recommend a cost reduction of 4, and 5 on high budgets.
A thread discussing it:
KillerElite goes into further depth 2 posts below.
Q: Does HotA have breakpoints?
A: Yes, see below. In general, they match up fairly closely with sprint/ww ones, and there are more available. Try to make sure that you are not barely below one when buffed with WotB. Other than that, don't stress over them too much.
Q: I want to use a DTWW/HotA hybrid with my Skorn. How much attack speed do I need?
A: Most of us advocate reaching the 17 tick breakpoint, which requires 1.67 APS when buffed with Wrath of the Berserker. With a non-IAS Skorn, this requires 42% IAS from gear. Nubtro suggests 43% in case you drop wrath of the berserker, as there is a breakpoint at 1.43 APS. With an 11% IAS Skorn, only 26% IAS from gear is necessary to reach the same breakpoint. The 18 tick breakpoint is significantly smoother. This requires 1.82 APS buffed, but it's recommended to also hit the 1.83 APS breakpoint for HotA if you're going this route. With a non-IAS Skorn, this requires 58% IAS from gear, or 7 slots. Don't attempt this without a very large budget. With an 11% IAS Skorn, this breakpoint requires 40% IAS from gear.
Q: Which rune of HotA should I use?
A: The most popular option is Smash due to its high proc coefficient and damage output. It synergizes well for dual wield barbs who use DTWW for their AoE damage. When relying on HotA for AoE damage, other runes can be preferable, as Smash reduces its effective area. Thunderstrike is my favorite, as it stuns mobs easily and consequently makes fury generation easy. Rolling thunder has a low proc coefficient, but has the highest area of effect. All 3 of these runes are worth consideration if you wish for HotA to be your primary source of damage.
Rolling Thunder: .40
The Devil's Anvil: .08
Note: as of now it isn't fully established how the animation lengths work with dual wielded weapons of different speeds. The table below assumes a single weapon or equal speeds for both. Big thanks to Nubtro.
Most effective farming builds will use sprint/wotb:toc/br:itf. That doesn't change for HotA. Even without ww, it is possible to perma-wrath through HotA and bash.
This is a basic build that should be fairly easy to use for a beginner and does not have high gear requirements:
Thunderstrike generally makes things easier by allowing you to generate fury off of a larger amount of mobs, and stunning them to make them less dangerous. One can also swap this for Smash for higher single target damage. Superstition is both an excellent source of fury, and provides excellent survivability. You'll notice that there isn't much room in the skill bar for war cry. The combination of rend:blood lust and superstition should prove to provide better defenses than war cry and much better offense. When you're running dry on fury, hit bash:instigation to top your globe off. RLTW tornadoes help with fury generation.
The following is a build that provides higher damage output and quicker movement, but has more difficult fury management:
Sprint:marathon provides higher movement speed than rltw. You no long have the fury gain from sprint tornadoes, instead have to move quickly from pack to pack, smashing and bashing as you go to keep fury high. Brawler generally gives the highest damage output for a third passive for HotA/rend builds, as trash mobs tend to clump up around you. Bash:punish provides another large source of damage. It's common to use a build similar to this, but with run like the wind instead of marathon. These runes can be adjusted according to your personal preference and gear.
Videos of "pure" HotA/rend builds:
Jim's with high-end gear (IAS Skorn): http://youtu.be/Z_Ul4X2aSCs
Silverfire's with top-end gear (dual wield): http://youtu.be/6P9tfgvplBk
Det0x's with top-end gear (dual wield): http://www.youtube.com/watch?v=QC1lwk-lQOU
Death's with high-end gear (Skorn): http://www.youtube.com/watch?v=dCkmpafmT-0
Corgon's with 10m in gear (dual wield): http://www.youtube.com/watch?v=_mifOEygNAY
Det0x's essence farming build:
Rend is swapped out for the added mobility of leap: death from above for added mobility. Being able to do this requires strong gear. He skips trash mobs with the intent of farming essences only.
MannerCookie's Merciless Assault build:
The following two builds from two of the best HotA barbs out there use the rolling thunder rune.
BangkokCanuk's low MP non-WotB xp farming build:
Det0X's HotA farming build:
Be aware that this build requires top-end gear to execute properly
They're becoming all the rage these days, and for good reason. DTWW gives the highest consistent AoE damage available to the barbarian class, and HotA the highest single target damage. I would advocate using HotA reduction (idealy 4 or 5) when using such builds, as they generally come without a fury generator. Using these builds effectively with a Skorn generally takes high-end gear. It's easier with dual-wielding, but the typical DTWW combo of an echoing fury mainhand and low DPS stat stick off-hand is far from optimal for HotA damage. An off-hand with the highest damage and crit damage possible benefits HotA significantly, and they aren't cheap. No matter what the weapon combo, you need to be comfortable with using a fury generator-less build, and your gear needs to be good enough to take punishment to generate fury while getting started. Consequently, these builds are more advanced in technique and gear requirements, but I highly advocate gearing towards them and using them.
The following are examples of very powerful hybrid specs.
DAKKON's DTWW/OP:KS/HotA build:
Death's DTWW/Rend/HotA build:
More videos with high-end gear:
Skorn video: http://www.youtube.com/watch?v=Cf7om8d_aPo
DW video: http://youtu.be/ci_qcDHT9N0
DW HOTA and 2h HOTA have the same tDPS given the same profile dps. 2h has the advantage of much higher Rend damage since it is based in the damage range of your MH weapon. DW hit's much faster and returns more fury making WOTB easier to keep up when dealing with fewer targets.
To maximize fury gains and tDPS, you should aim for a fully buffed HOTA tDPS of 100%. You want every HOTA to crit since only crits will return 15 fury from into the fray based on the 80% proc rate of HOTA Smash. You also want every HOTA to crit for the obvious DPS it gives over a non critical hit. This can be achieved without too much difficulty if you use the proper skills and have enough CC from gear. For example, if you have 35% from gear add 15% from passives + 5% starting amount+3% from battlerage + 10% from WOTB + 10% from OPKS, you will have a total of 78%. Each 5 fury in your globe gives an addtional 1% so a globe with 115 total fury will give an additional 23% if you only use HOTA when your globe is full.
HOTA reduction is an important number to calculate, IMO. This reduction is going to determine how much fury you are able to earn without spamming fury burning skills such as sprint or battlerage. I have a total APS of 2.76 with HOTA. This number is from d3rawr.com and looks to be the average of my two weapons. At 2.76 APS, With my -5 SOJ, I will burn 41 fury per second. That is 15 x 2.76 = 41.4. As long as I earn more than 25 fury per second, my WOTB timer will keep getting time added. The more fury I earn the faster my timer will reset.
A 2H weapon will have the same calculation but since you hit much slower, you will burn less fury and -HOTA reduction can be a bad thing. Assume you have a HOTA APS of 1.5 and a -5 ring. You will only burn 22.5 fury per second which means you will forever lag behind the 25 fury you need to add 1 second to WOTB. You will have to start using fury burning skills so that you can use more than the 25 you need to start resetting the timer. Since your HOTA CC relies on having a full globe when you use it, if you start burning fury you will never have a full globe when you go to use HOTA and your problems will start compounding. IMO, you should burn at least 25 fury per second while using HOTA. As an example, with 1.5 APS you want no more than -3 HOTA which means you will burn 27 fury per second. If you want to use a - 5 SOJ then you need to have at least 72% IAS with a 1APS 2h weapon. This will result in 1.72 x 15 = 25.8 fury burned per second.
Earning fury is another set of calculations. For 99% of your run you will probably be hitting multiple targets and taking damage. Taking damage returns fury but the amount depends on the MP level and the type of damage as well as the monster that is inflicting the damage. I have not seen any charts that detail this. This is simply my observation.
Once you figure out how much fury you are burning, you can take a look at the worst case scenario situation and all other fury gains will be easier. Worst case scenario being a frozen uber. Use my profile as an example, again. With 2.76 APS and a -5 SOJ, I will burn 41 fury per second. If I am hitting a single target, and assuming I have 100% HOTA CC, I am only going to earn on average 12 fury. 15 from into the fray x 80% proc rate of smash. That gives me a total earned of 33.12. I could use other skills like animosity for an extra 20% and the templar with resource regen for another 8%. This would bring my total to 42 fury gained per swing. This is enough to perma spam HOTA and always keep my WOTB timer at 0.
Of course, that will rarely happen. Another way to gain the extra fury to perma spam on a single target is to DW with a mightyweapon. Thanks to @Jim for pointing that out in another thread. The extra 3 fury per swing will also result in a fury surplus. You will lose 10% CC from your passive which will potentially cause some other problems but if you gear for it then you will be ok. Another great way to earn fury which I believe @MiSo pointed out was to use superstition. While tanking elites you are certain to be taking some elemental damage and the fury gains from superstition will keep you full.