The Harrowing

From Diablo Wiki

The Harrowing is the fourth and final chapter in Diablo II (excluding Lord of Destruction, the act which was added in Diablo II: Lord of Destruction expansion). The player travels to Pandemonium Fortress to put an end to Diablo's reign of Terror once and for all.

[edit] Summary

As soon as the player arrives in Pandemonium Fortress, Deckard Cain welcomes them to the Last Bastion of Light in the Burning Hells. He also tells the player to meet the Archangel Tyrael.

The distraught Archangel thanks the player for rescuing him in Tal Rasha's Chamber and asks them of a favor, to find and destroy the Demonic Vessel holding Izual.

The player carries out the Archangel's wishes and kills Izual's demonic host, freeing the Angel. Izual informs the player that it was he who told the Prime Evils of the Soulstone's power and that the demons had orchestrated a massive plan to gain the power of the Soulstones.

Hearing about this, Deckard Cain beseechs the player to destroy Mephisto's Soulstone at the Hellforge. The player does so and ends up killing the Armorer of Hell, Hephasto.

Seeing that the final path is clear, Tyrael prepares the player for their final battle, with the Lord of Terror himself. The player meets up with Hadriel, another Angel sent to keep an eye on Diablo's chamber, the Chaos Sanctuary. He informs the player that Diablo has not reached his maximum potential after possessing the Dark Wanderer's body and that the transformation has left him weak. So, before fighting Diablo himself, the player must confront three of his finest generals. The player eventually succeeds in defeating the three generals and obliterates Diablo. The player then destroys his Soulstone at the Hellforge before going to Harrogath.