Elite mode

Elite mode (previously and informally called Hard mode), not to be confused with heroic mode, refers to the increase in difficulty of a raid boss encounter resulting in increased rewards and/or achievements. This is accomplished by doing or not doing certain things that increase the difficulty of the boss fight. It is not possible to set an encounter to elite mode from the user interface (as compared to Heroic mode where it is possible), rather, specific objectives in the encounter must be completed to enable elite mode.

Elite mode versions of item drops were introduced in Mists of Pandaria. Before then, items awarded from an elite mode of an encounter were unique to that mode and were not dropped at all if the encounter was completed normally.

Ahn'Qiraj
Prior to the release of Wrath of the Lich King and the coming of real elite mode encounters, the Temple of Ahn'Qiraj was the first raid instance to have an encounter where the difficulty and loot were determined by the order you kill each boss (Silithid Royalty). Also worth noting that the Temple of Ahn'Qiraj was also the first instance to have optional bosses (Viscidus, Ouro and Silithid Royalty).

Zul'Aman
Zul'Aman was the second raid where loot varied depending on what the players did. In this case the loot was on a timer, the more bosses that were defeated before the time ran out the better loot was rewarded. In total four chests, one at each of the four first bosses were possible to obtain. The Amani War Bear from the last chest was removed in Patch 3.0.2.

Sunwell Plateau
The Eredar Twins initially dropped loot based on kill order: it was easier for the group to kill Grand Warlock Alythess before killing Lady Sacrolash, but killing Sacrolash first would yield more gear drops. When Patch 2.4.3 went live, the kill order ceased to matter, and the Twins would drop identical loot regardless of which one was killed first.

Obsidian Sanctum
Obsidian Sanctum was the first Wrath of the Lich King raid instance released with a elite mode boss encounter. If Sartharion was defeated while one or more of the Twilight Drakes was still alive, he would drop an additional item with a higher item level than his other loot. Sartharion gained additional abilities if one, two, or all drakes were left alive, and would receive aid from the minibosses during the fight. This lead to many groups overgearing for the encounter and hoping to kill Sartharion before the other drakes arrived. Even if the drakes killed the group, as long as Sartharion was defeated, he would drop the extra gear, and the drakes would despawn.

Ulduar
Ulduar took the concept further with 10 of the 14 bosses having elite modes. These are: Flame Leviathan, XT-002 Deconstructor, Assembly of Iron, Freya, Hodir, Thorim, Mimiron, General Vezax, Yogg-Saron, and Algalon the Observer. Algalon is WoW's first elite mode only encounter, and for this reason was made optional (skippable) as far as completing the instance is concerned.

Trial of the Crusader and beyond
After the introduction of Ulduar in Patch 3.1, Blizzard moved from calling 25-player raids "Heroic mode" (where 10-player raids were "Normal mode"), to having four modes, selected via the user interface: 10-player, 10-player Heroic, 25-player, and 25-player Heroic. Elite modes of encounters were phased out in favor of making the switch (to Heroic mode) via the UI.

This paradigm began with Patch 3.2 (Trial of the Crusader), and continued through the rest of Wrath of the Lich King and all of Cataclysm. Although, Trial of the Grand Crusader was tied to a specific system of limited tries to beat all bosses during the same lockout period and the more tries remaining at Anub'Arak's defeat, the more/better loots were in the Tribute Chest. The same tries system was used in Heroic Icecrown Citadel for some bosses but wasn't giving any additional rewards to players. Cataclysm first raid tier was also featuring an Heroic-Only Boss with limited tries : Sinestra in the Bastion of Twilight.

Mists of Pandaria reintroduced (And formally named) Elite mode, with the Protectors of the Endless encounter in Terrace of Endless Spring gaining an Elite mode in addition to Heroic mode. Similarly to Sinestra, Ra-Den was an Heroic-Only Boss with limited tries in the Throne of Thunder raid.

This, and future, encounters now have 9 tuning levels, with health pools, damage levels, and presence of abilities different for each tune:
 * 10-player:
 * 10-player normal mode
 * 10-player Elite mode
 * 10-player Heroic mode
 * 10-player Heroic Elite mode
 * 25-player:
 * 25-player Raid Finder mode
 * 25-player normal mode
 * 25-player Elite mode
 * 25-player Heroic mode
 * 25-player Heroic Elite mode

Silithid Royalty
The Silithid Royalty in the Temple of Ahn'Qiraj offers players 3 different methods. The easiest way to complete this encounter is to kill Lord Kri first, then Princess Yauj and finally Vem. The 'medium' way is to kill Lord Kri in second. The hardest way is to kill Lord Kri last. The rewards are determined by the order you kill the Bug Family. Each bug has some unique items in its loot table, while others are shared.

Sartharion
Sartharion in Obsidian Sanctum has 3 different hard modes. The three drakes, Vesperon, Shadron, and Tenebron can be killed to make the Sartharion encounter of normal difficulty or it can be increased to elite mode by leaving one or more of the drakes alive when starting the Sartharion encounter. Defeating Sartharion with the drakes up rewards an achievement and additional loot, increasing with additional drakes: / (one drake left), / (two drakes left) and / (all drakes left).

Flame Leviathan
Flame Leviathan in Ulduar has 4 different hard modes, with loot and badges increasing for each tower which is not destroyed, similar to Obsidian Sanctum. There are four towers in the area before the Flame Leviathan and leaving 1 or more of these towers up is increasing the fight difficulty by buffing the boss damage and abilities as well as its HP. On top of that, each tower is allowing the boss to enable the corresponding Orbital Countermeasure.

Several achievements are also given out depending on the number of towers destroyed. They are / (three towers destroyed), / (two towers destroyed), / (one tower destroyed), and / (all towers left up).

XT-002 Deconstructor
XT-002 Deconstructor has one elite mode. At 75%, 50%, and 25%, XT-002 Deconstructor's heart will be exposed. Destroying the heart (which has a multi-million HP pool) activates the elite mode, which heals XT-002 Deconstructor to full HP and gives him the buff Heartbreak, which increases XT-002 Deconstructor's damage done by 15% and his HP by 50% (60% in Heroic). Defeating XT-002 Deconstructor while killing his heart awards players the achievement / and additional loot.

The Assembly of Iron
There are two different hard modes for the Assembly of Iron. The normal strategy is to kill Stormcaller Brundir last (/). The medium elite mode is to kill Runemaster Molgeim last (/) which allows the Archivum Data Disc to drop, which begins the quest to unlock the Celestial Planetarium (And thus Algalon). The hardest way to do the encounter (And the method that rewards the hard mode loots) is to kill Steelbreaker last (/). The rewards are increased loot and achievements.

Hodir
Hodir's elite mode requires the raid to down him in under 3 minutes, preventing him from shattering the Rare Cache in the room (/). As of Patch 3.1.1, Hodir will not shatter the cache if he is downed mid-cast.

Thorim
Reaching Thorim within 3 minutes causes Sif not to despawn and assist Thorim in the fight. Meanwhile, she cannot be targeted and she nukes the raid. Unlike the normal mode Sif does not put the debuff Touch of Dominion to reduces his HP and damage by 25% (means 25% more damage and HP than normal mode) (/).

Freya
Freya has 3 different hard modes. The three Ancients, Elder Brightleaf, Elder Stonebark, and Elder Ironbranch can be killed to make the encounter of normal difficulty or it can be increased to elite mode by leaving one or more of the Ancients alive when starting. Defeating Freya with the Ancients up rewards additional loot and an achievement: / (one ancient left), / (two ancients left), / (all ancients left).

Mimiron
Mimiron's elite mode is activated by pressing the "Big Red Button" prior to the encounter. Pressing the button puts a 10-minute enrage timer on the encounter and increases the health and damage done of all the vehicles in the encounter by 25%, while fires spawn through the area as Mimiron's workshop self-destructs. (/)

General Vezax
To access General Vezax's elite mode, do not use the Saronite Vapors to regain mana. If nobody in your raid makes use of the Saronite Vapors, when the 8th (and last) Saronite Vapor is spawning, they will combine to create the Saronite Animus meanwhile a Saronite Shield spawns around General Vezax (which turns him immune to damage). After you killed the Saronite Animus, the shield will despawn and you can kill General Vezax. General Vezax will drop improved loot and reward the achievement /.

Yogg-Saron
There are four different hard modes for Yogg-Saron. The normal mode involves using the assistance of the four keepers - Freya, Hodir, Mimiron, and Thorim. The hard modes involve using the assistance of fewer Keepers. Yogg 1 Keeper was the common hard mode of the fight, as it was the one rewarding hard mode loots and required for the Ulduar Raid Glory. Yogg 0 Keeper was a way harder fight that was rewarding you with the Mimiron's Head mount (Which now drops at 1% chance).

The achievements related to this fight are: / (use three or fewer Keepers), / (use two or fewer Keepers), / (use one or fewer Keepers), and / (do not accept the help of any Keepers).

Algalon the Observer
Algalon the Observer is unique in that he has no normal mode. He is considered a "elite mode only" boss by Blizzard because to confront him you must defeat multiple bosses on elite mode.

Protectors of the Endless
The Protectors of the Endless encounter in the Terrace of Endless Spring is the first encounter to reintroduce elite mode since Ulduar. The new elite mode is separate and distinct from heroic mode, and there are five versions of loot available for this encounter: Raid Finder (ilvl 483), Normal (ilvl 496), Elite (ilvl 503), Heroic (ilvl 509), and Heroic Elite (ilvl 516).

The normal mode of the encounter requires killing Protector Kaolan first, then Elder Regail and Elder Asani in either order. Elite mode happens when the two elders are killed first and Protector Kaolan is killed last. Kaolan both has more health than the two elders, and much more annoying abilities.