Wrath of the Berserker is a Rage Barbarian skill unlocked at Level 30, transforming the Barbarian into a giant, hulking beast for a short period. While in this state, the Barbarian gains massive bonuses to both damage dealing and defensive stats.
Though the bonus is short-lived, with just a 15 second duration, it's possible to greatly extend the duration with skill runes and equipment that generates critical hits. Expert players with good equipment and specific builds can maintain this form indefinitely while fighting large groups of enemies, giving their Barbarian an enormous boost to killing power and survivability.
 Skill Rune Effects
The following is a very quick summary. See the Wrath of the Berserker rune effects page for a more thorough description of rune effects, or any of the individual rune pages for numbers, screenshots, blue quotes, and much more.
 Skill Design
This skill turns the Barbarian into a furious killing machine with bonuses to physical damage-dealing stats, and it also adds defensive bonuses as well. It provides a way of disposing tough monsters quickly, such as bosses or minibosses. This skill is an excellent demonstration of the design philosophy of the Berserker style Barbarian, where there is no such thing as too much power.
The most common use for Wrath of the Berserker is to enable the Thrive on Chaos rune effect, which adds one second of duration for every 25 Fury gained. This must be used in conjunction with skills, passives, and equipment that enable the Barbarian to generate huge amounts of Fury, and thus remain in the WotB form indefinitely. The most common and useful options are:
- Battle Rage with the rune effect Into the Fray. Battle Rage grants a 15% damage bonus and +3% critical hit chance, while Into the Fray adds a "a chance to gain 15 fury from critical hits." This is an essential skill to pair with WotB since it enables massive Fury gain.
- +Critical Hit chance: This must come chiefly from equipment, and gloves, bracers, shoulders, and rings are common sources of this bonus.
- The Sprint rune effect Run Like The Wind releases numerous small tornadoes that deal damage, but more importantly provide constant hit checks on numerous enemies in the area. This is the Barbarian's best source of numerous critical hits.
- Seismic Slam the rune effect Rumble causes tremors to remain in the hit area, which deal 30% weapon damage and create numerous proc checks for critical hits.
- Passive Barbarian Skills that boost Fury or Critical Hit chance:
- Ruthless -- This passive skill grants +5% critical hit chance and +30% critical hit damage.
- Weapons Master -- This passive skill grants +10% Critical Hit Chance when the Barbarian has a mace or axe equipped.
- Animosity -- This passive skill increases Fury generation by 10% and maximum Fury is increased by 20.
- Unforgiving -- You no longer degenerate Fury. Instead, you gain 1 Fury every 2 seconds.
 Base Skill
The following Barbarian passive provides a benefit to Wrath of the Berserker, runed or not:
The following Barbarian passives provide a benefit to Slaughter:
 Arreat's Wail
The following Barbarian passives provide a benefit to Arreat's Wail:
Wrath of the Berserker first appeared in the BlizzCon 2009 demo at Tier VI in the Berserker Skill Tree, and stuck around for BlizzCon 2010 as a Tier 7 skill. Unfortunately, in both demos Barbarians didn't have a high enough level to select it.
Skill tiers were removed for the July 2011 Press Event, allowing skills to unlock steadily from levels 1 to 30. Consequently, all skill levels were adjusted and Wrath of the Berserker became a level 29 skill. It was, however, demonstrated at the event. Kutako.com mentioned it in their hands-on report:
We see the Barbarian's Wrath of the Berserker, a special ability that transforms him or her into a dark giant beast capable of slicing through Diablo's minion hordes.
The Diablo III Beta started in September 2011, and while it ran, all of the skills continued to undergo extensive iteration. Skill changes varied from changing the levels the skills are unlocked, to changes in resource cost, damage, and even function. A few skills were removed altogether, and a few new ones were added. Also, the entire skill system received an overhaul with the Beta Patch 13 update in February 2012, with physical runes replaced by rune effects that automatically unlock at various levels for the different skills.
Wrath of the Berserker remained at level 29 when the beta started. With the Patch 13 changes, it was classified as a Rage skill and moved to level 30.
Wrath of the Berserker can be seen in action on video here:
You can find pictures in the Diablo III screenshot and picture gallery: