Diablo 4 Barbarian BuildDualZerker Whirlwind Barb

1. Use Rallying Cry as your Primary Fury Generation and Movement Speed skill that will help you generate all the fury you need to hold your Whirlwind indefinitley while active.
2. Cast Challenging Shout to buff yourself with 50% Overall Damage Reduction to tank enemy hits (Especially useful in Endgame Content). Try to apply as much as possible with Cooldown Reduction on gear, etc.. allowing almost infinite uptime for survivability.
3. Hit One enemy in the pack 3 times with Lunging Strike to gives us the Aspect of Expectant 30% Extra Damage buffs from our gloves, and also the 100%+ Extra Damage from the mortal draw glyph when casting your Whirlwind after. (Make sure to assign your Whirlwind to your 1H Weapons and Lunging Strike to your 2H Sword)
4. Cast War Cry on Boss Fights and against elites to shred HP with the Movement speed, damage bonus, and it also gives you the Berserking Bonus for 4 Seconds. Cast around 6 enemies or more if possible to get the the 10% Damage Buff.
5. Cast Wrath of the Berserker for Movement Speed, Damage, and Berserking Bonus as Berserking's damage is increased 25% per point of fury spent. This can generate a bunch of damage when coordinated with all of the other shouts.
6. Cast Whirlwind for Big Damage around as many enemies as possible to maintain constant max. fury. Snapshotting explained below for Whirlwind.
7. Finish pack of enemies, round up another large group of enemies, cast shouts to generate max fury again, and repeat this gameplay loop.

Snapshotting for this build means upon casting your whirlwind, there are some skills Whirlwind takes a snapshot of at the beginning of the cast to apply to your characters damage. 4 Primary skills should be maxed out before snapshotting your Whirlwind to deal the most possible damage Endgame.

War Cry - Upon Casting Warcry this skill gets snapshotted by your Whirlwind and deals increased damage if your WW is activated while this skill is still active.

Aspect of the Expectant - Here we want to hit an enemy 3 times with lunging strike before we cast out WW to get the 10% bonus from this aspect each hit and get a total of 30% bonus damage. This 30% lasts as long as you are still casting WW and will be reset once the WW cast is stopped.

Edgemaster's Aspect - This snapshots your current MAX resource pool and uses that as the damage Bonus % for the entire cast.Aspect of Limitless Rage - We want to get over our max fury to get the 60 Stack for 60% extra damage bonus before we cast our Whirlwind.

Adding all of these snapshot-able bonuses up this will take our damage from in the 200-300K range up to 1.5-2.5 Mil.

It is important we apply bleed to enemies as well as hit an enemy with Lunging strike and Cast challenging shout as well to give us the 50% DR from our Challenging shout, 20% instantly from hitting an enemy with a Basic Skill, and 20% from Bleeding enemies around us. This on top of all the DR from our other sources we already have.