Tyrael, formerly the Archangel of Justice, now the Aspect of Wisdom, is a mortal angel — something of a maverick to the High Heavens, and a stalwart defender of Sanctuary.
The Great Conflict
"Tyrael does not understand. He cannot see beyond the glory of battle. In time, he may. But that day is not yet here."
Tyrael in the Great Conflict
The Great Conflict was fought for time immemorial, and Tyrael was no exception in regards to waging it. As the Archangel of Justice, his exploits in battle became the stuff of legend. Off the battlefield, he administered the Courts of Justice.
Tyrael against demons
One such engagement was in battle against demon forces led by Diablo himself. The Lord of Terror was captured, with Tyrael and Auriel pointing out that holding him captive would serve their cause better than slaying the demon outright, knowing that he would return. However, Imperius carried out his own form of justice regardless, slaying the Lord of Terror.
In another engagement, Tyrael faced the Lord of Sin, Azmodan. However, a fellow angel, Ardleon, called for aid, and despite being poised to deliver a killing blow to the Lord of Sin, Tyrael came to his comrade's aid.
Izual served as Tyrael's lieutenant during the aeons of war, but was captured by Hell during an assault on the Hellforge. Inarius also served under him and tried to make him see the futility of the conflict, but Tyrael would not be swayed. Either way, the Great Conflict ground to a halt on its own—the Worldstone had disappeared, and the forces of Heaven and Hell could only blame each other before realizing that a third party had absconded with the artifact.
The Sin War
"I did call them abominations...and I was wrong! My vote is for them...For I would see what they might become...and marvel in it."
—Tyrael vouches for humanity's continued existence
In the course of the Sin War, Heaven would come to discover what Hell had already done so—Sanctuary. A world created by rogue angels and demons led by Lilith and Inarius. A world inhabited by the race of Men—beings descended from the nephalem, who had been brought into the world through the coupling of angels and demons. Venturing into the world, Tyrael spirited away Achilios, telling him that he had need of him. He forced him to target his Edyrem comrades including their leader Uldyssian, seeing them as key threats and unnatural blights upon the face of Creation. Achilios managed to refuse however, surprising Tyrael. He later convinced the edyrem that Uldyssian had been possessed by Malic. Surveying the situation, Tyrael was satisfied. Despite earlier considerations, he would not have these "abominations" allying with Heaven. They had to be eliminated due to the threat their inherent powers posed. And with the edyrem fragmented, Sanctuary's potential defenders would not be able to stand against his justice.
As such, Tyrael was among the Heavenly Host who descended upon the world, meeting in battle with the Edyrem and the Demonic Hordes themselves. Uldyssian, realizing that his growing power risked the destruction of the world, sacrificed himself to end the battle, saving Sanctuary, all those he loved, and perhaps most importantly of all, his own humanity. It was an act that touched Tyrael and swayed his heart—he had called these beings abominations. Yet no abomination would have made such a sacrifice as Uldyssian had.
Tyrael and co. decide the fate of Sanctuary
The Angiris Council convened to discuss Sanctuary's fate. Imperius opted to eradicate Inarius and Lilith's progeny while Auriel and Itherael voted in favor of humanity, believing that humanity's potential to serve the Light could surpass even their roles and that the Conflict might be ended for good. Malthael abstained. Thus, the deciding vote would be left to Tyrael—were he to side with Imperius (as everyone suspected he would), Sanctuary would be destroyed, as a tie would still result in their original goal being carried out. Tyrael however, sided with humanity. They would be left to their own devices, free to choose between Light and Dark.
"I am a wanderer; I have seen more than most would ever imagine. That is merely my nature."
"Will you give me your name?"
"My name is Tyrael."
—Tyrael conversing with Siggard
In 302, Tyrael was present in Entsteig. Having taken the disguise of a golden-haired man, he met Siggard on the Night of Souls. Siggard, having supposedly survived the Battle of Blackmarch from two days past, wanted to return to the area. Tyrael pointed him northwards to his destination, but recommended that Siggard instead head south for Entsteig. Siggard nonetheless headed north.
The two reunited at Brennor, which was about to come under siege by the forces of the archdemon Assur. Siggard was incredulous that Tyrael was an archangel and that those around him knew so, but as Tyrael pointed out, he'd never asked. But to answer the question of what aid he could provide, all Tyrael could offer was advice. As Assur was protected by the Glyph of Invincibility, Tyrael advised the fortress's defenders to focus on his army instead.
Brennor fell, but Siggard was nonetheless able to defeat Assur in single combat, despite his glyph making it impossible for any living being to slay him. Meeting him afterwards, Tyrael revealed what Siggard had begun to suspect, that he had in fact died at Blackmarch, but his soul had not been claimed by death. Tyrael advised him that it was unlikely that he would find rest through revenge, but an act of love might suffice. Yet for the immediate future, Siggard would be a good ally against the forces of Hell. With that, Tyrael faded away and departed.
The Dark Exile
Tyrael would at times make sojourns into Sanctuary. However, greater tragedy was to come—Hell had not given up on Sanctuary, believing that humanity could be swayed to their cause. This was a view not shared by the Lesser Evils however, and in what became known as the Dark Exile, the Prime Evils were banished into Sanctuary. However, they were still capable of bringing woe to the mortal realm, and by the time Tyrael discovered their actions, they'd been active for decades. This concerned Tyrael greatly—Sanctuary had been spared by a margin of one vote when the Angiris Council had discussed its fate. If Heaven learned that Hell was focused on Man, it might carry out what he and Imperius once, and perhaps still, intended. As such, he kept silent. He would intervene on Sanctuary's behalf, and do so alone.
Tyrael in the Tomb of Tal Rasha
Fashioning three soulstones out of the Worldstone, Tyrael gathered a number of mages, forming a group called the Horadrim. Over many years, they hunted down the three Primes. Mephisto fell first, and Baal second, though he shattered the soulstone meant for him in battle. There was not enough time to reformulate the soulstone, but with the suggestion that a mortal heart could serve as a surrogate soulstone, Tal Rasha stepped forward, plunging the stone into his flesh. Tyrael assured him that his sacrifice would not be forgotten, and led the mages to a tomb beneath the sands of Aranoch. There, the Horadrim built a binding stone etched with runes of containment. Tal Rasha ordered that he be bound to the stone, and as the other mages looked on in sorrow, Tyrael jammed the soulstone shard into Tal Rasha's heart, transferring Baal's essence into the mage's body. Sorrowfully, the Horadrim departed, leaving Tal Rasha to wrestle with Baal's writhing spirit for all eternity.
Finally, after a decade of searching, the Horadrim confronted Diablo in the lands of Khanduras. The soulstone worked and was hidden away within a labyrinthine cave system near the River Talsande. Tyrael appeared before the Horadrim one last time, commending them for having achieved a victory despite their losses. He declared that the site would have to be guarded and to this end, the Horadrim erected a monastery over the site.
Tyrael had succeeded—the Primes were captured, Sanctuary still existed and Heaven was none the wiser. However, he had not counted on the Prime Evils' ability to exert their will over Men. Over time, Mephisto would corrupt the Zakarum faith and Diablo would do likewise through the archbishop Lazarus.
The Return of Evil
"Stop! The beast contained herein shall not be set free — not even by you."
—Tyrael confronts the Dark Wanderer
Tyrael attacking the Dark Wanderer
In 1263, Diablo escaped from his prison by corrupting the spirit of Aidan, hence referred to as the Dark Wanderer. He headed east, seeking to free his brothers, Mephisto and Baal. Baal was first, bound to Tal Rasha's body. Tyrael appeared to stop the release and did battle with the Wanderer. However, another had traveled with the Wanderer—Marius, and thanks to the demon's manipulations, released the Lord of Destruction. Tyrael telepathically ordered Marius to take Baal's soulstone to the Temple of Light in Kurast, where he would find a gateway to Hell and by extension, the Hellforge, where the stone could be destroyed. Immediately afterwards, Tyrael was ensared by Baal and bound to the Binding Stone.
Tyrael greets the heroes
Tyrael came to be freed by a group of heroes who were pursuing the Dark Wanderer. They traveled to the Pandemonium Fortress, where he guided them to face Izual and Diablo himself. He dared not help them directly, as he had been weakened by Baal and feared that direct action could lead to the High Heavens discovering the danger Sanctuary was in. The heroes prevailed however, and Diablo's soulstone was destroyed, as was the stone of Mephisto.
Marius, however, had not been so courageous. He had failed to venture into Hell and consequently, the stone was still in his possession. Possession that switched to Baal himself, now the last Prime Evil active in Sanctuary. Baal marched on Mount Arreat, intending to corrupt the Worldstone and in doing so, shackle humanity to Hell's cause. To this end, Tyrael transported the heroes to Harrogath, but weakened as he was, could not face Baal directly.
Tyrael Destroys the Worldstone
The heroes came to defeat Baal, but were too late to prevent him corrupting the Worldstone. After transporting the heroes to safety, Tyrael cast his sword into the stone, shattering it. The resulting explosion destroyed Tyrael's physical form and rendered Arreat and the surrounding lands a barren wasteland. Worse still, although humanity had been saved yet again by the Archangel of Justice, the destruction of the Worldstone meant the world was open to both Heaven and Hell.
Return to the High Heavens
In Arreat's shadow
Eventually, Tyrael regained physical form. He returned to the Heavens and summoned El'druin to his side. The act of reformation was unprecedented, as usually angels were replaced through the Crystal Arch, a new angel embodying their aspect rather than rebirthing the original angel who was deceased. At some point after this, he advised Urzael to search Sanctuary for the missing Malthael, as the Archangel of Wisdom had taken an interest in humanity prior to his disappearance.
The End of Days
"You cannot judge me. I am justice itself! We were meant for more than this! To protect the innocent! But if our precious laws bind you all to inaction ... then I will no longer stand as your brother."
—Tyrael's parting words
Tyrael confronts Imperius
In 1285, evil threatened Sanctuary, this time from the Lesser Evils Belial and Azmodan. He promised that Man would not face the coming darkness alone. Imperius however, had since discovered his transgressions, and was unmoved by Tyrael's defiance. The two came to blows before Tyrael declared that if Heaven would not intervene on Man's behalf, he'd do so himself. Tearing off his wings, Tyrael deliberately chose to become mortal, sacrificing his angelic essence. In doing so, Tyrael hoped to demonstrate to the High Heavens that laws could be bent for a greater good. He had a degree of control over the process, and as he intended to walk amongst humans, taking on their form would serve his goals. Furthermore, by becoming mortal, he would no longer be bound by his nature as an angel, as the other members of the Angiris Council were. Such an act was without precedent amongst angelkind.