The Harrowing

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

With only three quests, Act IV is the shortest act of the game. Prior to the expansion, the game would be completed after killing Diablo. With the coming of Lord of Destruction, players gain access to another Act. After defeating Diablo, players are sent to speak with Tyrael, who then opens a portal to the city of Harrogath.

Before one goes blindly rushing deeper into the realm, however, it should be known that players without the expansion must complete The Harrowing without the aid of any mercenaries. The only help you can get comes from other players in Battle.net. It is also recommended to have some solid resistances; not only do you have to deal with the constant Inferno casts by the Balrog-type demons, but the Doom Knights can deal damage of any element.

Summary
The player arrives in the Pandemonium Fortress, the "Last Bastion of Light" in the Burning Hells. There the player meets Deckard Cain and the Archangel Tyrael.

The Archangel thanks the player for rescuing him in Tal Rasha's Chamber and asks them of a favor. A long time ago, his lieutenant, Izual, was captured by the Lords of Hell and twisted by their perverse power. Now a fallen angel, Izual roams the Plains of Despair, trapped within a demonic vessel. The hero is sent to free Izual's spirit by destroying the demon.

The player carries out the Archangel's wishes and kills Izual's demonic host, freeing the Angel. However, Izual's spirit informs the player that it was he who told the Prime Evils of the Soulstones' power and how to corrupt them. Tyrael realizes the danger: with the power of the Soulstones at their command, the forces of Hell would become unstoppable. Hearing about this, Deckard Cain tasks the player to destroy Mephisto's Soulstone at the Hellforge to prevent his spirit from manifesting itself in the mortal realm ever again.

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 sanctum, the Chaos Sanctuary. The player fights his way through hordes of demons in order to confront the Lord of Terror within his own lair. The hero manages to destroy the demon after an intense battle, and obliterates his Soulstone at the Hellforge.

The player returns to the Pandemonium Fortress, where he is hailed as a champion. However, one last brother remains...

Quest Necessity and Tips
For one to earn successful navigation to Act V or, in the case of Classic players, the next Difficulty level, the hero must complete Terror's End, although the other 2 quests offer rewards hard to pass up for the player:
 * Completing the Fallen Angel will bestow +2 Skill Points on your hero to spend as you see fit
 * Completing the Hellforge will reward you with some good to top quality Gems, and if playing in the expansion set, a Rune.

Trivia

 * Development of Act IV was completed in February/March of 2000.