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.

Nihlathak, the town’s only surviving Elder, doubted the potency of their spell, and so he struck a bargain with the Lord of Destruction.

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.

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.

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.

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.

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.