This guide will show you how to play a Level 70 Whirlwind Barbarian in Diablo 4, with a frost twist. The build focuses on chilling enemies and dealing high damage, allowing you to quickly clear content in Tier IV and beyond. It utilizes the Penitent Greaves as a crowd control mechanic, leaving a trail of frost that chills and slows enemies. The build is easy to set up and can be customized for different playstyles and goals, making it suitable for both beginners and experienced players.

Key Features:

Insane clear speed for dealing with large packs of elites in seconds.
High movement speed for quickly navigating through dungeons.
Shouts play a crucial role in this build, providing resource generation, damage reduction, and damage boost. Cooldown reduction is a priority.
Two-Handed Axe Expertise is recommended for the weapon technique to maintain vulnerability on enemies.

To make it easier to understand which equipment to use and the desired affixes, I'll categorize them based on slots. Remember, Cooldown Reduction should be a top priority, as it directly impacts the uptime of your shouts and ultimate ability, significantly boosting your performance.

Helmet:
Legendary Aspect: Aspect of Grasping Whirlwind. This aspect is essential, as it pulls enemies towards you, allowing for efficient crowd control and increased efficiency.
Affixes: Cooldown Reduction, Maximum Life, +Stats, +Damage While Berserking, +Total Armor.
Unique Equipment: Harlequin Crest. This highly coveted helmet offers tremendous affixes, including a 4-rank improvement to all your skills and damage reduction. If you're fortunate enough to acquire it, equip it and slot the Grasping Whirlwind aspect elsewhere.

Chest:
Legendary Aspect: Aspect of the Protector. This aspect enhances your defensive capabilities, providing damage reduction and improved toughness.
Affixes: +Damage, +Damage Reduction, +Armor, +Challenging Shout, +Rallying Cry.
Unique Equipment: Rage of Harrogath. This unique chest armor complements the build with increased crit damage and boosts to your Whirlwind and Challenging Shout.

Gloves:
Legendary Aspect: Aspect of Anemia. This aspect amplifies your critical strike chance and Whirlwind damage, greatly enhancing your damage output.
Affixes: +Critical Strike Chance, +Whirlwind Damage, +Stats, +Armor.
Unique Equipment: Gohr's Devastating Grips. These gloves are a fantastic choice, as they increase your crit damage and critical strike chance, further amplifying your damage potential.

Waist:
Legendary Aspect: Aspect of Numbing Wrath. This aspect synergizes with the build, offering additional damage after killing an elite, increased total armor, and improved Rank of War Cry.
Affixes: +Damage After Killing an Elite, +Total Armor, +Rank of War Cry, +Stats.
Unique Equipment: Temerity. This unique pants slot is an excellent choice, boosting your maximum life, damage, and resistances.

Greaves:
Legendary Aspect: Ghostwalker Aspect. These boots focus on movement speed and overall stats, granting you superior mobility and survivability.
Affixes: +Movement Speed, +Stats, +Armor.
Unique Equipment: Penitent Greaves. These boots are highly recommended for their frost trail effect, which chills and slows enemies. If you don't have access to them, prioritize movement speed and look for other useful affixes.

Two-Handed Bludgeoning:
Legendary Aspect: Aspect of the Dire Whirlwind. This aspect is crucial for maximizing your Whirlwind damage, ensuring you decimate enemies swiftly.
Affixes: +Damage to Close Enemies, +Vulnerable Damage, +Critical Strike Damage, +Stats.
Unique Equipment: The Grandfather. This exceptional weapon is highly sought after, offering significant boosts to your Whirlwind and overall damage. If you manage to acquire it, it will greatly enhance your performance.

First One-Handed:
Legendary Aspect: Aspect of the Expectant.
Affixes: +Damage, +Stats.
Regular Weapon: Slot a regular weapon to accommodate this aspect.

Second One-Handed:
Legendary Aspect: Conceited Aspect.
Affixes: +Damage While a Barrier is Active, +Stats.
Regular Weapon: Slot a regular weapon to accommodate this aspect.

Two-Handed Slashing:
Legendary Aspect: Aspect of Limitless Rage.
Affixes: +Damage, +Stats.
Unique Equipment: The Grandfather is recommended if available, as it synergizes well with this aspect.

Amulet:
Legendary Aspect: Edgemaster's Aspect. This aspect offers crucial affixes such as cooldown reduction, damage bonuses, and overall stats.
Affixes: +Cooldown Reduction, +Damage Bonuses, +Stats.
Unique Equipment: Aim for The Eye of Etlich, a legendary amulet that boosts your damage, toughness, and provides resistance against ranged attacks.

Rings:
Legendary Aspect: Aspect of Echoing Fury (First Ring).

Affixes: +Damage Bonuses, +Critical Strike Chance, +Vulnerable Damage, +Stats.

Unique Equipment: Echoing Fury is an excellent choice, enhancing your damage and critical strike chance. Alternatively, any legendary ring with relevant affixes can be used.

Legendary Aspect: Bold Chieftain's Aspect (Second Ring).

Affixes: +Damage Bonuses, +Life After Killing an Enemy, +Stats.

Unique Equipment: The Wailing Host is a solid option, providing damage, toughness, and bonuses after killing an enemy.

As you progress in Diablo 4, remember to keep an eye out for rare and legendary items that can further optimize your build. If you're looking to enhance your gameplay even further, consider purchasing cheap Diablo 4 gold from reputable sellers such as u4gm to acquire valuable items and upgrades that can propel your character to new heights.