Black Temple

The Black Temple is the fortress-citadel of Illidan Stormrage, Lord of Outland. It was once known as the Temple of Karabor, and has changed hands many times over the generations. The entrance to the Black Temple does not appear to be its main gates, but rather an instance portal set in a breach in the southern battlement, below the ruins of Karabor. It no longer has a required attunement.

Background
Before the shattering of Draenor, the Black Temple was once called the Temple of Karabor, a sacred site to the draenei which served as the refuge of the Prophet Velen. Shortly after the formation of the Horde, Gul'dan ordered the temple conquered. Upon discovering the Burning Legion had been manipulating the orcs, the draenei leaders knew they could no longer defend their holdings and ordered their forces to withdraw to Shattrath City and Karabor. During the ensuing battle, the draenei were helped by arakkoa such as Grizzik, and against all odds the outnumbered defenders were able to push the relentless orcs back.

In response Gul'dan and the Shadow Council decided to ignore the Shadowmoon clan's warnings about the Dark Star, an ancient god of the Void that was actually the fallen naaru K'ara. They conducted a ritual to call on the Dark Star in their war against the draenei and channeled it at Karabor. A pillar of Void energy ripped through the heavens and slammed down on Karabor, driving many draenei defenders to madness while many others died instantly. Velen called on his powers to keep the Void at bay and rally the survivors to Karabor's harbor, but the Dark Star had forever darkened Karabor, and it became known as the Black Temple and was taken by the orcs.

After their defeat, the captured draenei clerics of Karabor were marched out, told that they were to be taken to Hellfire Citadel as prisoners of war. The warlock Teron'gor murdered each and every last one of them in cold blood outside of the walls.

At some point, the orc J'argg Bloodfyre came here and obtained the blood of Mannoroth.

During the Invasion of Draenor, it was used as a fortress by Ner'zhul and his Shadowmoon clan forces. After the planet's destruction and its transformation into Outland, the Black Temple was taken over by the Burning Legion. It was used as a "prime staging ground for the Burning Legion's campaign of destruction." When Illidan the Betrayer fled to Outland after the Third War, he ousted the Temple's ruler - the pit lord Magtheridon - and claimed his throne as the lord of the blasted world. Following his defeat at the hands of Arthas Menethil, Illidan returned to the Black Temple where he resides to this day. Neither his activities or mental state are known at this time. While Malfurion has stated that Illidan has become mad and delusional, believing that he killed Arthas and accomplished the mission Kil'jaeden had sent him on, it says on the Burning Crusade website that "Illidan lives in fear that he will be discovered by his powerful enemies — most notably Arthas, the new Lich King, and the remaining Lords of the Burning Legion." Despite the bitter retribution of his enemies, Illidan has begun to tighten his grip on Outland from within the profaned sanctum, where he awaits any and all who would challenge his rule.

The Black Temple was besieged once by the Sha'tar forces of High General Auralion, but these draenei were destroyed by Val'zareq the Conqueror of the Crimson Sigil and their leader captured. Some times later, the Burning Legion unleashed the fel reaver Doomwalker on the Temple.

Later, another army combining the forces of the Scryers and Aldor attacked again, this time helped by the Illidari rebel Akama and Maiev Shadowsong, former prisoner of the Betrayer.

Kanrethad Ebonlocke and Jubeka Shadowbreaker infiltrated the Black Temple, evading the Ashtongue Deathsworn under Akama who had reclaimed the temple after Illidan's death. Entering the Shrine of Lost Souls, Kanrethad recognized it as the power source that allowed Illidan to control demons without their being corrupted by the fel energies endemic to the Legion, and theorized that it had been originally intended as the power source to replace the Sunwell when Kael'thas Sunstrider and his blood elves aligned with him. Since Illidan's death, it grew in strength and power, waiting to be harnessed. The two warlocks prepared a crystal to absorb the arcane magics within the Shrine, leaving it to do its work when they heard Ashtongue patrols hunting them.

Later adventurer who studied warlock magics soon came on their trail. Reclaiming the now-empowered crystal and taking it to the summit, the warlock witnessed the opening of a massive gateway, and from it stepped Kanrethad in a monstrous demonic form, utterly corrupted by absorbing too much fel energy. Though Kanrethad's powers were formidable, the warlock persevered long enough for Jubeka to arrive and fulfill Kanrethad's earlier request to banish him.

Following the break-in by the Council of the Black Harvest, Akama had his Sha'tari priests erect a holy barrier to protect the temple from fel magic. The Illidari, seeking to secure Akama and his knowledge about the Legion, sent Illidari-loyal Broken to infiltrate it and gain any valuable information. Matron Mother Malevolence bypassed the holy barrier using the Grimoire of Arcane Ways, and the Illidari invaded the temple.

Geography
The 4 bosses after Supremus can be fought a non-linear order, but all must be defeated in order to unlock Mother Shahraz and continue to the end.

Attunement
Though the attunement is no longer required to gain entrance to the Temple, you can still complete it. Below is a short guide on how to.

First you have to complete Akama's Promise. Then players adventuring in the Serpentshrine Cavern will have access to a quest from a Broken NPC named Seer Olum in Fathom-Lord Karathress's room (the quest is entitled The Secret Compromised). After delivering a message to Akama, he informs Illidan of Kael'thas' treachery in order to attempt to prove his loyalty (Illidan believes him, but is still suspicious). You will then need to slay Al'ar in the Eye of Tempest Keep so that Akama can convince Illidan he is still loyal.

The next part of the attunement involves killing Rage Winterchill, a lich boss, which is also the first boss in the Battle of Mount Hyjal instance. After this you are sent to Xi'ri outside the gates of Black Temple. You must slay the demonic Illidari forces outside the Temple in order to provide a distraction for Akama and Maiev to slip into the Temple undetected. After that Xi'ri rewards you with the Medallion of Karabor.

Loot
The Black Temple is a level 70 raid instance in Outland, containing tier 6 drops and.

Quests

 * Seek Out the Ashtongue
 * Redemption of the Ashtongue
 * The Fall of the Betrayer

Achievements

 * The Black Temple (achievement)
 * The Black Temple Guild Run
 * Warglaives of Azzinoth (achievement)

Official preview
From The Black Temple in Under Development:

The Black Temple
Originally founded as a Draenei temple, this plot has been conquered and despoiled many times throughout the history of Outland, removing any spiritual grace it may have once held. The Black Temple has been the stage of the Orc Horde's blood curse, fortress for the then-mortal Ner'zhul, and a prime staging ground for the Burning Legion's campaign of destruction... Most recently, it has been claimed as home by Illidan, where he and his minions make their bid for power over the remnants of the shattered planet. Now, it is up to you to face the malefic forces of Illidan and his minions in hopes of freeing Outland from chaos and tyranny.

Black Temple is a 25-person raid dungeon located in Shadowmoon Valley.


 * Explore an ancient site steeped in Warcraft lore 
 * Gain access to more than a hundred new and  items, including tier-6 armor sets 
 * Choose your path through a nonlinear level-70 raid dungeon, as you make your way to... 
 * Face Illidan himself!

From Black Temple Preview in Under Development:

Long ago on Draenor, the Temple of Karabor was the center of draenei worship. But the devout priests who prayed there are long dead, slaughtered by marauding, demoniacally corrupted orcs. In the massacre's aftermath the warlocks of the Shadow Council seized the structure and bestowed upon it a new name: the Black Temple.

For years the Shadow Council bloodied the Black Temple with foul demonic rituals, but after the Second War the dark spellcasters fell to the Alliance's devastating invasion of Draenor. The shaman Ner'zhul hastily opened several dimensional portals in order to stage a retreat, and the resulting magical backlash ripped the world apart. In what had become the fractured realm of Outland, Ner'zhul's portals were a strategic advantage that appealed to the demon general Magtheridon, who quickly seized the Black Temple as his seat of power.

Magtheridon commanded many of the orcs remaining in Outland and bolstered his army with Legion forces streaming in through the portals. The pit lord's might remained unchallenged until Illidan the Betrayer decided to claim the Black Temple for himself. Illidan and Magtheridon fought a desperate battle on the temple walls, but in the end the pit lord proved no match for the wielder of the Twin Blades of Azzinoth. Illidan battered Magtheridon to the point of death, but the thrill of victory was short-lived....

The skies of Outland darkened as Kil'jaeden himself appeared before Illidan, furious at Illidan's failure to destroy the Lich King. The Betrayer was forced back to Azeroth for a disastrous attack on Icecrown Glacier. Bloodied by the death knight Arthas but not fully beaten, Illidan returned to Outland and established his throne within the Black Temple. And yet, despite Illidan's efforts to seal Ner'zhul's portals, Kil'jaeden's wrath will not be denied. Even now the merciless Doomwalker batters at the temple gates.

In the RPG
Illidan the Betrayer stands as the lord of Outland and rules his domain from a massive, black iron ziggurat. Ner'zhul was originally responsible for this hulking edifice, but now blood elves, naga and Illidan's few other allies roam its corridors. The naga live in underground sewers, and the upper levels teem with blood elves, traps, evil and death. Rumors tell that beneath the citadel sprawls a great prison; trapped within are heroes from previous wars, languishing in unknown solitude.

Trivia

 * In The Frozen Throne, the Black Temple was called "Black Citadel" and was situated in Hellfire Peninsula instead.
 * The adjective for something coming from Karabor is Karaborian.
 * A joke Black Temple attunement quest line was published on the 1st of April 2007. This was a reference to the Hyjal attunement quest that technically requires players to complete most of the high-level dungeons in the game. Hyjal attunement was also a step in Black Temple attunement.
 * Another joke of Blizzard about the Black Temple was the Priests of Baa'ri faction.
 * The planet Azeroth is visible in the southern sky from the courtyard where you fight Supremus. It is also visible from the temple summit, although the view is cloudy.
 * In Hearthstone, the Black Temple card back was rewarded for achieving Rank 20 in Ranked Season 2, which took place during May 2014. The flavor text reads: "“Fel Flame Green” is always in fashion at the Black Temple."
 * An unknown entity time-traveled to the Black Temple right before the original Illidari attack on Mardum and modified the battleplans for the incoming assault to make them even better. Vormu of the bronze dragonflight came too late to stop this modification of the timeline.
 * In the trailer for the Black Temple raid, it shows the scene where Gul'dan's men attack the temple.
 * The Temple changed hands many times: starting with the draenei of Velen, it was then taken by the Shadow Council of Gul'dan, and after that the Shadowmoon clan of Ner'zhul. After the destruction of Draenor, the demonic forces of Magtheridon settled there, before to be ousted by Illidan Stormrage's forces. After his death, the Temple was re-taken by the Ashtongue tribe of Akama, in a sense the rightful owners of the place.
 * In April 2003, the Black Temple at level 70+ (level 70 was originally planned to be the level cap in vanilla) was among the planed instances for original World of Warcraft.

Speculation
It is possible that Karabor was named after K'ara, the naaru that was ejected from the Genedar in the chaos of its crash and came to be known as the Dark Star to the orcs of Shadowmoon Valley.