The story
After the defeat of Diablo in the base game, Tyrael—now a mortal—recovers the Black Soulstone, the artifact that contains the essence of all seven Great Evils. He fears it’s too dangerous to destroy, so he hides it deep within a Horadrim tomb. But before they can seal it, Malthael, the former Archangel of Wisdom turned Angel of Death, shows up.
The cinematic shows Malthael as this haunting, ghostlike figure in a black cloak, wielding twin sickles. His wings are now wisps of smoke instead of light—signaling he’s not exactly Heaven’s poster boy anymore. He annihilates Tyrael’s Horadrim guards effortlessly and takes the Black Soulstone, declaring his plan to end all demonic corruption by wiping out humanity itself (since humans carry demon essence from their Nephalem ancestry).
Thematically, it flips the series’ dynamic—evil isn’t just from Hell anymore. Heaven’s gone rogue. Malthael sees “purity” through extermination, which makes him arguably more terrifying than Diablo.
It’s basically Diablo meets Death itself. The trailer sets the stage for the expansion’s story: humanity caught between the remnants of Hell and a fallen angel who thinks genocide is salvation
