https://www.icy-veins.com/d3/barbarian-leveling-build-guide
https://www.icy-veins.com/d3/barbarian-leveling-and-fresh-70-guide

Helm: Flawless Royal Diamond (or highest available for CDR) or Flawless Royal Amethyst (or highest available for Toughness)
Torso and Pants: Flawless Royal Ruby (or highest available)
Weapon: Flawless Royal Emerald (or highest available)

• Bane of the Trapped — staple multiplicative damage increase. Note that the gem is self sufficient, proccing itself when fighting in melee range, where the Barbarian fights almost by default.
• Bane of the Stricken — almost mandatory gem for Greater Rift progression, as it is designed to whittle down the scaling health numbers of monsters with a percentage-based increase on successive attacks.
• Boon of the Hoarder — synergizing with other farming mainstays like Avarice Band and Goldwrap, this gem will not only keep you rich, but also sped up and safe during normal rift farming.
• Bane of the Powerful — the speedfarm counterpart to Bane of the Stricken, Bane of the Powerful offers a solid overall damage and survivability increase as long as your killing speed does not fall behind the timer of the gem.

Situational gems

• Esoteric Alteration is a defensive cornerstone in facetanking builds, protecting you against bursty elemental affixes.
• Simplicity's Strength amplifies primary skill damage, which is particularly useful for a Frenzy build.
• Taeguk is a great addition to a channeler Barb, which you will be by using anything Whirlwind-related.

Kanai's Cube choices are highly build- and content-specific, making them hard to summarize. Generally speaking, Barbarians should store the powers of the following items in the Cube as soon as they have the materials available:
x The Furnace
x In-geom
x Messerschmidt's Reaver
x Oathkeeper
x Ambo's Pride
x Fjord Cutter
x Blade of the Tribes
x The Gavel of Judgment
Fury of the Vanished Peak
Bastion's Revered
x Standoff
The Three Hundredth Spear

x Pride of Cassius
x Dread Iron
x Girdle of Giants
x Lamentation
x Vile Ward
x Mortick's Brace
x Bracers of Destruction
Bracers of the First Men
x Skular's Salvation
x Vambraces of Sescheron
Lut Socks (boots)
x Aquila Cuirass
x Nemesis Bracers

x Band of Might
x Obsidian Ring of the Zodiac
x Ring of Royal Grandeur
x Convention of Elements
x Avarice Band

https://www.icy-veins.com/d3/whirlwind-gr-wastes-barbarian-bis-gear-gems-paragon-points
https://www.icy-veins.com/d3/barbarian-whirlwind-gr-build-with-wrath-of-the-wastes

complete Wrath of the Wastes set
Convention of Elements
Skull Grasp
Rolls-wise, this build aims for a general CDR goal of 38%+, achievable by rolling maximum Cooldown Reduction on one weapon, the natural CDR on The Flavor of Time, CDR roll on the Pauldrons of the Wastes, a Flawless Royal Diamond in Helm of the Wastes, and Paragon Points.

Whirlwind Barbs also benefit greatly from Area Damage, aiming to obtain it as a fourth main stat on Pauldrons of the Wastes and Gauntlet of the Wastes, your rings, and potentially both weapons. Whirlwind skill % should be rolled on both Helm of the Wastes and Sabaton of the Wastes. Cuirass of the Wastes and Tasset of the Wastes are best left to pure toughness stats.

Both rings will ideally feature Crit Chance, Crit Damage, Area Damage and an open Socket. Your first ring will be the 2.6.1-revised Skull Grasp Skull Grasp, bringing a 400% multiplicative damage increase to Whirlwind. Your second ring will be taken by the elemental damage boost of Convention of Elements, whose rotation you will need to learn and time to maximize the benefits of the short-lived Physical damage cycle.

On the topic of jewelry, aim for as perfect of an elemental amulet as you can. The ideal rolls are Crit Chance, Crit Damage, an open socket and Physical elemental damage. The recommended amulet is Hellfire Amulet of Strength, since it allows you access to an additional synergistic passive like Nerves of Steel, Animosity or Brawler. The former favorite The Flavor of Time should now be slotted on your follower, and its power will be transferred to your character via the Emanate mechanics.

Pride of Cassius is considered the go-to belt for Greater Rift pushing; the only defensive option for the slot, it can more than double the duration of your Ignore Pain activations. To make matters slightly more difficult, the unique property of Pride of Cassius has a range instead of being fixed, and you should actively seek and gamble for the highest 6-second extension to ease the strain on your Cooldown Reduction.

With its addition, Mortick's Brace (Bracer) grants you the effect of every Wrath of the Berserker rune: from the staple 50% damage increase of Insanity, through the burst damage additions of Arreat's Wail and Slaughter, to the protective and utility bonuses of Striding Giant and Thrive on Chaos.

The two mandatory weapons for the build — and his namesakes — are the Bul-Kathos's Oath set, Bul-Kathos's Solemn Vow and Bul-Kathos's Warrior Blood. Essential to the playstyle by providing its signature mobility and fluid resource management, these weapons will be your primary concern to obtain with excellent rolls (a combination of high weapon damage, Area Damage and CDR) when pushing the build to its limits.

For Offense stats, try to obtain Whirlwind % bonus on both the helm and boots (maximum of 30%), Physical elemental damage on both the amulet and wrists (maximum of 40%), Crit Chance and Crit Damage within a 1:10 ratio (ideally over 50% and 500%, respectively), and Area Damage of 100%+. Whirlwind Barbs require a minimum of 38% Cooldown Reduction to maintain Ignore Pain, Wrath of the Berserker and Threatening Shout on every Physical rotation of Convention of Elements.

For Defense stats, aim for a life pool between 700-900k; dropping as much as you can for offense as you grow accustomed to the build. You will mostly sustain through Blood Funnel, but some extra healing will come from Life per Fury Spent from Thrive on Chaos (attained via Mortick's Brace).

All augmentations on gear should be done with your main stat, Strength.

Note that the stat suggestions below portray an ideally rolled item with stats listed in relative order of importance. The first four of them are main stats, and the latter two — secondary stats. If your item lacks and is unable to be rerolled into the primary stats outlined below, especially for a stat higher on the list, strongly consider its replacement. Perfecting Secondary stats is mostly a case of hyper-optimization and is not a case for discarding an item, except where noted.

2. Paragon Points
In the Core section, max out Movement Speed to the 25% cap. Normally this is done by dumping the first 50 Core Paragon points into Movement Speed, but if your boots have an imperfect roll with Movement Speed as a stat that you cannot replace, adjust the necessary point investment accordingly by simply subtracting your roll from the 25% max. After that dump as much as you comfortably can into Strength, but feel free to invest into Vitality if you feel yourself lacking in toughness. Adding to Maximum Fury is not necessary in this build.

In the Offense section, max out CDR, Crit Damage, Attack Speed and Crit Chance in that order. In Defense, prioritize All Resistance, then Life %, then Armor, and finish off with Life Regeneration. In Utility, build up Area Damage and Life on Hit first, then finish off with Resource Cost Reduction and Globe Radius.

Slot Paragon Points
Core
Movement Speed up to 25% cap
Strength
Vitality (up to personal preference)
Maximum Fury (up to personal preference)
Offense
Cooldown Reduction
Critical Hit Damage
Attack Speed
Critical Hit Chance
Defense
All Resistance
Life %
Armor
Life Regeneration
Utility
Area Damage
Life on Hit
Resource Cost Reduction
Globe Radius

3. Gems
Bane of the Trapped Bane of the Trapped is a potent source of additional damage, as it is its own multiplier in your total damage calculation. The gem will be procced by its own level 25 bonus when in melee range of the enemy.

Taeguk is a rare hybrid of defense and offense among the legendary gem options, and continued Whirlwind Whirlwind channeling will ensure that your stacks remain capped for a constant, well-rounded benefit.

Bane of the Stricken occupies the third and final jewelry socket. Building up your damage multiplicatively in prolonged fights and with a level 25 bonus specifically targeting Rift Guardians, this gem is designed to assist AoE heavy builds in their struggle against single target, high HP enemies. The Whirlwind Barb is a prime example of such a build, and Bane of the Stricken is considered mandatory in GR progression. When doing lower tier content (standard rift farming or speed GRs), Bane of the Powerful should be used in this socket for a well-rounded, speed clearing-oriented bonus.

Slot Gems
Jewelry:
Bane of the Trapped
Taeguk
Bane of the Stricken
Bane of the Powerful (alt speedfarm)
Helm
Flawless Royal Diamond
Torso and Pants
Flawless Royal Ruby (Damage)
Flawless Royal Diamond (Toughness)
Weapon
Flawless Royal Emerald

4. Kanai's Cube
The power of Echoing Fury in your weapon Cube slot is highly synergistic with the Whirlwind Barbarian, as it provides a scaling Attack Speed and Movement Speed bonuses, both of which are vital to this IAS-centric, mobility-dependent build.

Whirlwind Barbarians naturally expose themselves to danger in the thick of the fight, so the addition of Mantle of Channeling in the armor cube slot is natural. This legendary shoulder increases your damage during Whirlwind channeling by 25%, while simultaneously reducing damage taken by the same amount.

Obsidian Ring of the Zodiac; a powerful option for Whirlwind Barbarians that makes this cooldown-heavy build much easier to manage. Benefiting greatly from the attack speed inherent to dual wielding, as well as the Bul-Kathos' set, it allows for permanent uptime of crucial abilities like Ignore Pain and Wrath of the Berserker.

5. Follower
The recommended follower for this build during solo GR progression is the Scoundrel due to his powerful crit buff, allowing you brief windows of extra damage that are well suited to the strengths of this build.

Diablo 3 Followers

6. Legendary Potion
The preferred potion for this build is Bottomless Potion of the Leech due to its Life per Hit bonuses, which synergize perfectly for the high attack speed and sustain-through-attacks playstyle of the build.