We are going to share the best Barb build with you in this Ultimate Barbarian Leveling Guide for Diablo 4 Season 3 so as to dominate the game. Regardless of whether you have previous experience or not, this guide will prepare you with everything needed to efficiently and effectively level up your Barbarian. 

• Build Breakdown
• Skills and Rotation
• Gear Essentials
• Paragon Board and Passives
• Build Planner
• Final Thoughts

↖ Build Breakdown

Basically, this leveling build is mostly about increasing Berserker's Rage damage buff, resource regeneration and movement speed. The goal here is to have always high Fury level and keep Berserker's Rage active via using Berserking abilities.

Advantages

• Great mobility
• Massive destruction
• Short cooldown periods
• Fast cleaning up(Hit and Run)

Drawbacks

• Charge pathing is a little you know
• Needs Ancestral Charge & Giant Strides to function
• Missing your attacks may lead to severe consequences.
• Not a good Duriel build

↖ Skills and Rotation

As a main attack, Leap combines mobility with Fury generation. This also proactively activates Berserker's Rage guaranteeing that your first hit of Charge skill can benefit from its damage boost. 

Charge is mainly used to generate Fury while doing damage. Each Charge immediately gives a significant amount of fury without any lingering effects. Double Swing acts as a filler when it's necessary for you to maintain your Fury levels.

On the other hand, Iron Skin coupled with Iron Warrior is what I would go for as my defensive ability because apart from providing solid protection it also purges poison which might be a life saver during leveling.

↖ Gear Essentials

The rotation of skills should be complemented by the gear. Some key items include:

• - Yitz's Lament (or similar): These stats should support build focus on Fury and damage.
• - TI-Bolt's Grandstand: It is vital for an enormous damage boost as well as having infinite fury.
• - Berserker's Raiment: You should pick equipment that causes bleeding effects thereby supporting Blood Rage while increasing cooldown reduction.
• - Ghost War Treads: Such boots will make you move faster which is very important in this fast paced build.
• - Brawler's Clasp: This augments Charge with an AoE explosion; totally perfect for Max Fury builds.

↖ Paragon Board and Passives

Your Paragon Board for instance will prioritize damage boosts for Berserking skills, cooldown reduction for sustained Berserker's Rage uptime, and survivability enhancements. Big Damage Boost and Disent B are the most important passives to maximize your build's effectiveness.

↖ Build Planner

For detailed skill and gear arrangements please check out the link on the description which will take you to the build planner. The planner will give you optimized routes for Paragon Board as well as show you best ways of spending your skill points to make your Barbarian reach its potential during leveling.

Planner Link: http://tinyurl.com/swxamu73

↖ Final Thoughts

This is quite a powerful but versatile Barbarian leveling build. It can be a good starting point for players beginning from scratch in Season 3 since it works great even without many unique items. As you progress, keep tweaking your gear and adjusting strategy so as to keep dominating Diablo 4.