Akarat's Champion

Akarat's Champion is a Conviction skill in Diablo III.

In-game
When activated, transforms the Crusader into an entity of holy fire, encased in the sacred armor of the Order. Visually, Akarat's Champion bears some resemblance to Avatars of the Order, but is seemingly more powerful. Iron Skin armor does not visually show up while this skill is in effect.

While active, in addition to damage and Wrath generation buff, the Crusader is also immune to all forms of Crowd Control, and clears them when the spell is cast.

Damage buff is multiplicative to other similar effects.

Runes

 * Fire Starter: for the duration, also burns any enemy damaged by either of the Crusader's attacks for 460% damage as Fire over 3 seconds. The chance to ignite an enemy is reduced by the Proc Coefficient of the skill in question, effect stacks, but is not renewed.
 * Embodiment of Power: increases additional Wrath generation to 10 per second.
 * Rally: activating Akarat's Champion also reduces remaining cooldowns of other skills by 12 seconds. This effect only happens once per activation.
 * Prophet: gain 150% additional Armor while Akarat's Champion is active. The first time the Crusader suffers fatal damage while in this form, they do not die, instead being healed to full Life. The latter effect can only happen once per activation.
 * Hasteful: also increases Attack Speed by 15% for the duration.

Non-rune enhancements

 * Baleful Remnant (Legendary Two-Handed Flail): each enemy killed while Akarat's Champion lasts is turned into an Avatar of the Order for 10 seconds, dealing 100% damage per attack.
 * Akkhan's Addendum (Legendary Two-Handed Flail): adds effects of the Prophet and Embodiment of Power runes to the manually selected one.
 * Armor of Akkhan Set (Set Bonus for 2 items): while Akarat's Champion lasts, the Crusader gains a 50% reduction to all resource costs.
 * Armor of Akkhan Set (Set Bonus for 4 items): also reduces the cooldown of Akarat's Champion by 50%.
 * Armor of Akkhan Set (Set Bonus for 6 items): also increases damage done by 2000% and reduces damage taken by 50% while Akarat's Champion is active.
 * Halcyon's Ascent (Legendary Amulet): activating Akarat's Champion causes nearby enemies to jump uncontrollably for 6-8 seconds.

Development
Originally, the skill itself allowed the Crusader a second chance upon taking fatal damage in earlier versions of the game, gave him/her a significant bonus to attack speed, and the Rally rune had a chance on attack to reduce remaining cooldowns by 1 second. As of patch 2.0.5, the former effect was moved to the Prophet rune, the second effect moved to Hasteful rune (replacing the movement speed bonus) and the latter effect was greatly weakened.

Trivia

 * Akarat refers to a Xiansai ascetic in the Diablo universe, the holy prophet of Zakarum faith.
 * This skill (with Prophet rune) is one of the two ways to be saved from dying by an active skill, the other being Self Sacrifice.
 * This is the Crusader's transformation skill which boosts powers and changes appearance, each class (barring the Witch Doctor) has one and all of them give the added bonus of immunity to Crowd Control; the other class equivalents are: Vengeance (Demon Hunter), Wrath of the Berserker (Barbarian), Epiphany (Monk), Land of the Dead (Necromancer), and Archon (Wizard).