From the moment of reality’s creation, the angelic legions of the High Heavens and the demonic hordes of the Burning Hells waged an unending war known as the Eternal Conflict. After eons of battle, individuals from both armies grew weary of fighting and sought out a new home where they could co-exist peacefully.
Using the powers of a massive artifact called the Worldstone, they created Sanctuary, a realm hidden from both the Heavens and the Hells.
The demons and angels dwelling on Sanctuary came to mate with each other, spawning powerful hybrids known as nephalem - the first generation of humans. In time, the angels grew fearful of nephalem potential, and tuned the Worldstone to limit their offspring's power. Slowly, over generations, humanity forgot the secrets locked away in its blood.
Ultimately, the Heavens and the Hells learned of Sanctuary's existence, and clashed across the world in the horrific Sin War. After the fighting was brought to a standstill, both sides agreed to cease their battles on Sanctuary, leaving mankind to its fate. Yet, Diablo, Mephisto, and Baal—the Prime Evils and leaders of the Burning Hells—plotted to use humans as tools of war.
This goal bred dissent among lesser demons, who revolted. Hell's legions were devastated, but they'd exiled the Prime Evils to Sanctuary. The archangel Tyrael, one of Heaven's leaders, noticed the Evils in the human world and covertly formed the Horadrim, a group of magi, to hunt the Primes. Armed with soulstones—relics that could contain the Primes' essences—the Horadrim imprisoned their quarry, and hid the souls of the Three throughout Sanctuary.
Over two centuries passed without machinations from the Prime Evils, until the human king Leoric chose Tristram for his domain. Unbeknownst to Leoric, a malevolent presence lurked beneath the tiny town: the imprisoned Lord of Terror, Diablo.
Eventually, the confines of his Crimson Soulstone weakened, and Diablo was able to reach into the minds of the townsfolk above. Under the demon’s influence, one of Leoric’s aides—the Archbishop Lazarus—released Diablo.
With his true master freed, Lazarus endeavored to bend the king to demonic ends. He whispered to Leoric of an imaginary threat from the nearby country of Westmarch, leading the monarch to dispatch his eldest son, the warrior Prince Aidan, with an army.
Lazarus then abducted the distracted king’s youngest son, Prince Albrecht, so that Diablo could possess the child and regain physical form.
As Diablo drank in the child’s terror, the evil beneath Tristram began to spread throughout the town.
Aidan returned, vowing to rescue his brother and cleanse Tristram. Adventurers from all over the world were drawn to Aidan’s quest, including a rogue from the Sisterhood of the Sightless Eye, a Vizjerei sorcerer from Kehjistan, and a number of other resilient warriors trained in an array of weapons and armor.
The heroes were aided by several of Tristram’s surviving villagers: Griswold the Blacksmith forged and repaired the party’s equipment; Adria the Witch provided them with magical books and potions. Deckard Cain, the last living Horadrim, used his knowledge to guide their mission.
Lazarus was slain beneath Tristram, and Aidan challenged Diablo, who had possessed Albrecht’s body, twisting it into a harrowing monstrosity. Aidan destroyed Diablo’s manifestation… but he could not destroy the Crimson Soulstone. Fearing that Diablo would remain free to corrupt more innocents, Aidan resolved to contain the demon—by plunging the soulstone into his own forehead.
Weary, Aidan returned to Tristram, but the town’s celebrations did nothing to calm the dark essence that haunted his mind. The prince soon departed, heading to the east in search of answers… and salvation.
Though he wrestled with Diablo’s influence, Aidan was slowly driven to fulfill the demon’s overriding purpose: freeing the other Primes. As Aidan traveled through the Rogue Monastery, the base of operations for the order known as the Sisters of the Sightless Eye, Diablo’s possessing spirit conjured vicious demons who drove the monastery’s inhabitants from their home. Marius, an old vagrant who had taken refuge in the Monastery, found himself miraculously unharmed during the attacks.
Unsure if the horrors he had witnessed were tricks of his opium-addled mind, Marius followed Aidan, whom he referred to as the “Dark Wanderer.”
A group of heroes, driven to expunge the darkness, gathered in a small encampment constructed by the surviving rogues. Among them:
A barbarian from Mount Arreat; An amazon from the Skovos Isles; A paladin of the Zakarum faith; A sorceress from Kehjistan, and A necromancer from the eastern jungles.
After rescuing Deckard Cain from demonic imprisonment, the heroes cleansed the infested Monastery under his guidance, but they were too late to catch Aidan.
Accompanied by Marius, Aidan had traveled to an eastern tomb where the great Horadrim Tal Rasha once sacrificed himself, thrusting the Amber Soulstone into his chest to imprison Baal, Lord of Destruction.
Inside the tomb, the archangel Tyrael clashed with Aidan. Meanwhile, Baal managed to free himself by tricking Marius into removing the Amber Soulstone from Tal Rasha's withered body.
Aidan and Baal overpowered Tyrael and imprisoned him within the tomb, but not before the archangel commanded a whimpering Marius to take a shard of Baal's soulstone into the Burning Hells and destroy it, an act which would banish the Lord of Destruction (or any Prime Evil) from Sanctuary.
By the time the heroes arrived at the tomb, Marius and the Prime Evils had gone. The champions quickly liberated Tyrael, who urged them to follow Marius's path and ensure the success of his desperate venture.
Humanity’s heroes pursued Baal and Aidan towards Travincal, holy site of the Zakarum religion, where the Evils freed their brother Mephisto from his prison. United once again, the Primes put their plan to dominate humanity into action—Diablo cast off Aidan’s mortal flesh and traveled through a portal to rally Hell’s legions, while Mephisto remained on Sanctuary to ensure none interfered with his brother.
When the heroes arrived in Travincal, they were forced to battle not only Mephisto but also the corrupted luminaries of Zakarum. After a vicious confrontation that rattled the very stones of Mephisto's lair, humanity's champions cast down the Lord of Hatred and carried his soulstone through the portal to Hell.
Deep inside the Hells, the heroes shattered Mephisto’s soulstone upon the Anvil of Annihilation—then tracked Diablo to an unholy cathedral scored by ages of lava and rivers of blood. It was on this battleground that the heroes clashed with the Lord of Terror, pitting all of their valor and might against his timeless malevolence. At long last, Diablo was bested, his Crimson Soulstone sundered in the heart of Hell.
Meanwhile, Baal had traveled north on a mission to corrupt the Worldstone, turning all mankind to the side of evil. First, the Lord of Destruction plotted to avoid the fates of his brothers. He tracked down Marius, who—gripped with fear and unable to destroy the Amber Soulstone—had sought refuge in an asylum. Disguised, Baal fooled Marius into giving up the soulstone… then cruelly ended his life.
Armed with the Amber Soulstone he’d plucked from Marius’s dead hands, Baal personally led an assault upon the northern lands of Arreat, site of a great mountain sacred to the mighty barbarian tribes. His goal was the mountain itself: the resting place of the Worldstone used to forge Sanctuary.
Baal’s hordes ravaged the north, destroying each barbarian fortress save the small town of Harrogath, where several mystic Elders sacrificed themselves to weave a protective spell around their home.
Nihlathak, the town’s only surviving Elder, doubted the potency of their spell, and so he struck a bargain with the Lord of Destruction.
The demonic army would spare the people of Harrogath in exchange for the Relic of the Ancients, an artifact which would allow Baal to enter Mount Arreat unchallenged by its spectral guardians.
The heroes who defeated Diablo pursued Baal to the north, where they were joined by two newcomers. One was an assassin of the Viz-Jaq’taar, an order created to hunt down renegade sorcerers. The other, a druid from the woodlands of Scosglen, commanded the forces of nature and wore the forms of beasts.
With Tyrael’s aid, the band of heroes fought their way through the devastated northern wilds, breaching the vanguards of Baal’s army to reach Harrogath.
In town, the heroes uncovered Nihlathak’s gambit, bested the traitorous Elder and raced for the summit of Mount Arreat, only to find that Baal had already moved into the mountain’s heart. Before they could give chase, they were forced to squander precious time defeating Arreat’s guardian Ancients while Baal began his malefic work within the Worldstone chamber.
Inside, the heroes confronted the Lord of Destruction, and vanquished him in a ferocious battle. Though he fell before their blades and invocations, Baal had already corrupted the Worldstone, an act that threatened to spread strife throughout Sanctuary.
The archangel Tyrael took decisive action to save humanity. He hurled his angelic sword, El’druin, into the Worldstone, destroying the object that created Sanctuary. The surrounding land—including nearby barbarian settlements—was annihilated in a catastrophic explosion, and the mortal world was exposed to the gaze of the Heavens and Hells.
With the Worldstone destroyed, Sanctuary's role in the Eternal Conflict was forever changed. People largely forgot the horrors of an earlier age, and the town of New Tristram sprung up not far from where Diablo once dwelled beneath the earth.
But Deckard Cain hadn’t forgotten. He brought his adopted niece Leah to New Tristram, and continued to study the evil that had once crept from the cathedral. Cain was convinced that it was only a matter of time before doom would threaten Sanctuary again, and, for 20 years of relative safety, his warnings were easy to ignore… until a star fell from the heavens.
The star struck Tristram’s old cathedral, sending Cain plummeting into a crater and Leah rushing for help.
Stories of the fallen star attracted heroes from all over Sanctuary, including
A roving barbarian, survivor of Arreat's destruction; A vengeance-driven demon hunter; A monk from the monasteries of Ivgorod; A witch doctor from the umbaru people, and A wizard from the island nation of Xiansai.
Each of these individuals demonstrated unparalleled abilities, reminiscent of the nephalem born to angels and demons long ago.
The heroes answered Leah’s plea for help and found Cain, who had survived the impact, fighting for his life against skeletal abominations reanimated by the fallen star’s energies. Investigating the crater, they discovered that the fallen star was but a man, one with little recollection of his arrival in Sanctuary.
There were few clues to the stranger's identity: an ominous portent he could barely remember (though he was certain of its importance), and his sword, which had shattered when he struck Sanctuary.
After two decades of expecting new horrors to befall Sanctuary, Cain identified the man’s plight as key to understanding the coming darkness, and tasked the nephalem with retrieving the sword pieces.
Although the heroes successfully retrieved the fragments, Maghda—a cultist of the Lesser Evil Belial—attempted to seize the shards and mortally wounded Cain before fleeing from Leah and the heroes. As his final act on Sanctuary, Cain repaired the sword, and passed away before the eyes of his grieving niece. Cain’s suffering was not entirely in vain: reunited with his weapon, the stranger revealed himself as the fallen angel Tyrael, who had sacrificed his divinity to warn humanity of the arrival of two demon lords.
The Lesser Evils who had once cast Diablo and his brothers out of the Burning Hells—Belial, the Lord of Lies, and Azmodan, the Lord of Sin—were loose on Sanctuary, resuming their war to dominate mankind.
Together with the nephalem, Leah and Tyrael pursued Maghda to the desert city of Caldeum. They cornered Maghda within demon-infested Alcarnus, where they finally avenged Cain’s death—but the heroes learned a dark truth from the witch before she breathed her last.
Her master, Belial, the Lord of Lies, was hidden deep within Caldeum, manipulating its people from the shadows. Tyrael and Leah searched the city sewers for evidence of the demon lord, but only found Belial’s minions and their captive: Adria, Leah’s long-lost mother, the same witch who once provided assistance to Aidan and his companions in their fight against Diablo.
Conflict with the forces of evil had forced Adria into hiding years ago, and she had reluctantly left Leah behind. Both women were grateful for their reunion, but Adria quickly revealed the gravity of her presence in Caldeum. Belial's minions had captured her in search of the Black Soulstone, an artifact which could trap the souls of the Prime and Lesser Evils, banishing them from Sanctuary.
The artificer of the Black Soulstone, a Horadrim traitor known as Zoltun Kulle, was the only one who knew of its location, and he had been dead for centuries. Using Leah's magic, the party summoned a shade of the mad wizard and struck a bargain: Kulle would share the path to his buried magical archives and the soulstone within… in exchange for his resurrection.
Once Kulle was restored to life at the heart of his lair, he summoned forth the Black Soulstone, but was surprised to see the crystal humming with the souls of five of the seven Evils. Over twenty years, Adria had carefully marked the essences of the five demon lords so that they would become trapped in the stone.
Suspicious of the witch and her intentions, Kulle offered the nephalem a deal: work with him to cast down the Heavens and Hells, and reign together over Sanctuary. The heroes rejected the proposal, and were forced to contend with Kulle’s forbidden magic.
With the Black Soulstone in their grasp, the nephalem returned to Caldeum to imprison Belial… only to find the city besieged by his forces. Acting swiftly, the heroes forced their way into the imperial palace and unmasked Belial, who had disguised himself as Hakan II, child Emperor of Caldeum.
In his fury, the Lord of Lies nearly tore the imperial palace apart, and the nephalem along with it—yet the heroes overpowered Belial and trapped his soul within the Black Soulstone.
With peace restored to Caldeum, the nephalem prepared to hunt for Azmodan, but Leah had already received a mocking vision from the Lord of Sin.
Boasting about his knowledge of the Soulstone, Azmodan exulted, for his entire hellish host had begun invading Sanctuary from Arreat Crater.
The fortress of Bastion’s Keep, originally built near Mount Arreat to “contain the barbarian threat,” had nearly fallen to Azmodan’s armies by the time the heroes arrived. Even as the nephalem halted Azmodan’s attempts to breach the keep’s walls with demonic siege beasts, pockets of demons snuck past the defenses and made their way inside, killing huddled civilians and wearing down the beleaguered defenders of humanity.
Following Adria’s guidance, the party of heroes traversed the depths of Arreat Crater to crush the Sin Hearts, demonic artifacts from the Realm of Sin that empowered Azmodan’s armies.
In the core of Arreat Crater, the nephalem confronted the Lord of Sin. Azmodan unleashed the terrifying powers of Hell against the heroes, transforming his lair into a warren of decay and corruption.
At last, like Belial before him, Azmodan was defeated, his soul imprisoned within the Black Soulstone.
The victorious heroes returned to a grisly scene—atop the keep’s parapets, Tyrael was bound in arcane chains, and the blood and bodies of dead guards formed a ritual circle around Leah. As Adria plunged the Black Soulstone into her daughter’s flesh, she disclosed an awful truth: she was a servant of Diablo, and Leah—her child with Aidan, Diablo’s vessel—would usher in the return of the Lord of Terror.
Diablo’s awesome presence immediately subsumed Leah’s mind and body, transforming her utterly. Triumphant at her master’s return, Adria fled, leaving Tyrael and the nephalem horrified by the betrayal.
With the Black Soulstone in his grasp, Diablo devoured the souls of Mephisto, Baal, and the four Lesser Evils, and thus absorbed the power and malice of all lords of the Burning Hells.
He tore open a portal to the Diamond Gates of the High Heavens, at last in reach of his ultimate desires: eradicating the realm of his enemies, and reigning supreme over creation as the Prime Evil.
Diablo arrived at the Diamond Gates of Heaven wearing Leah’s form, but Imperius, the Archangel of Valor and commander of Heaven's forces, saw through the illusions of his ancient enemy, and scorched the demon’s false visage away.
Diablo’s true, terrible form was revealed, and the two fought bitterly until Diablo defeated Imperius and shattered the Diamond Gates. While Hell’s forces had besieged Heaven many times, they had never before managed to breach its gates—until this moment.
Once the Gates fell, the remaining members of the Angiris Council, Heaven's angelic leadership, were swiftly scattered.
Rushing to halt the despoiling of Heaven, Tyrael and the nephalem pursued Diablo through the open portal. There, they encountered a wounded and defeated Imperius, who blamed them for the ascension of the Prime Evil and the ruination of the High Heavens.
Diablo’s desecration of Heaven had been merciless. Scores of Hell’s most powerful, avaricious demons flooded through Hell Rifts. Angels were twisted into demons. Despair gripped the legions of the Heavens.
Undeterred, the nephalem fought their way through the conquered High Heavens—seeking the guidance of Itherael, Archangel of Fate, and rescuing Auriel, Archangel of Hope—before ultimately confronting Diablo atop the Crystal Arch, the source of Heaven’s power and the lifeblood of all angels.
Empowered by the souls of the Evils, Diablo unleashed ceaseless horrors upon the nephalem, even drawing them into his reality-warping Realm of Terror.
But the nephalem succeeded where the forces of the High Heavens could not, and, after a titanic conflict, finally rent Diablo’s physical manifestation into ash.
With Diablo vanquished, the hosts of the High Heavens set to rebuilding the ruin of their home.
Tyrael rejoined the Angiris Council as the mortal Aspect of Wisdom—a quality he knew would be sorely needed in the days ahead. He strove to heal the pain and distrust that spread through Heaven in the wake of Diablo's invasion, and to forge a true alliance between angels and mankind…
…but the specter of the Eternal Conflict continued to loom over his hopes for unity.
After Diablo was defeated and trapped in the Black Soulstone, the Angiris Council resolved to secure it within the High Heavens, but Tyrael doubted this solution. He recruited powerful humans from all over Sanctuary and dubbed them the new Horadrim, the first since the death of Cain. With their help, Tyrael stole the Black Soulstone from the High Heavens and planned to conceal it beneath the ruined city of Corvus.
Meanwhile, an ancient presence contemplated Tyrael’s undertaking. Malthael, the former Archangel of Wisdom, had become tormented by the mysteries of creation. He had abandoned his brethren and, in his search for the nature of souls, had become the Aspect of Death.
After the nephalem defeated the Prime Evil, Malthael decided to exterminate all beings of demonic heritage—including humanity—to end the Eternal Conflict. He attacked the new Horadrim and seized the Black Soulstone. His army of Reapers, a terrifying host of angels and undead, began to slaughter the people of nearby Westmarch and harvest scores of souls. With each human soul collected, Malthael’s power increased.
Malthael spirited the Black Soulstone to another realm: the Pandemonium Fortress, front line of the Eternal Conflict. Here, Malthael would reshape the Soulstone to consume all demonic essence in Sanctuary.
With the help of a crusader of the Zakarum faith, the nephalem confronted Malthael. In combat, Malthael shattered the Black Soulstone and devoured the released soul of the Prime Evil, devastating the battlefield with the powers of Hell and Death. After a grueling conflict, the combined might of the nephalem overcame the Aspect of Death. Malthael vanished in a blast of energy, releasing all the souls he had consumed—including Diablo.
… And Tyrael wondered if his nephalem allies, who had now bested champions of both Heavens and Hells, would one day fall to the same corruption that brought low even the greatest of Archangels.