Long after Inarius and Lilith have secretly constructed Sanctuary for the Nephalem - - the descendants of angel and human, the council of Archangels met to determine humanity's fate Diablo IV Gold. Tyrael cast the decisive vote, as such, he'd be held accountable for his decision by all of the Angiris Council, leading to him becoming mortal prior to what transpired in Diablo 4 all for the sake of mankind. His role in the new game is still unclear, but there are some likely ways this pivotal figure could be involved in the future of the series.
Diablo 3 is a deep dive into Tyrael's story, as he turns into the Fallen Star by tearing off his own wings and plummeting to Sanctuary that is where descendants of Nephalem reside. By joining forces with a powerful descendant, Tyrael is able to eliminate the Primitive Evils and gains charge of his Black Soulstone. After the Archangel of Death, Maltheal, went after the stone, and then took on all of his comrades He was Tyrael's who took his friend to Pandemonium to defeat death itself.
Tyrael decides to remain in his mortal form . He then joins his angelic brethren and becomes both his Aspect Justice as well as of Wisdom. Diablo 3 ends with him looking to see if his new mortal companion, who might be corruptedin the future, will one day become the next threat towards Heaven, Hell, and Sanctuary as well as the very existence of life itself. There's a reason that Aspect of Justice and Wisdom probably won't stand by as Inarius marches an army upon Hell in search of his former lover, Lilith.
The latest Diablo 4 cinematic trailer from Blizzard is a scene of Inarius looking down Lilith and armies on both their backs. While this footage doesn't include Tyrael's direct involvement, his development of Horadrim and the influence he has on the Paladins from Sanctuary implies that he's definitely involved. Light and dark clash on the battlefield, while the now-dead Tyrael is a middleman buy Diablo 4 Gold.