Since the beginning of time, the forces of Order and Chaos have been engaged in an eternal struggle to decide the fate of all Creation. That struggle has now come to the Mortal Realm...and neither Man, Demon, nor Angel will be left unscathed...

In Diablo II: Lord of Destruction, you will return to follow the path of Baal, the last of the Prime Evils, into the Barbarian Highlands of the north. Traveling with hordes of demonic minions, Baal intends to corrupt the powerful Worldstone, which protects the whole of the mortal plane from the forces of Hell.

You will face a new series of quests and challenges to prevent the vile minions of the underworld from destroying the world of Sanctuary.

Expansion Set Features

    * Two new character classes (the Assassin and the Druid) each with 30 unique skills/spells

    * One new Act set in the Barbarian Highlands

    * Many new monster types, including bosses and uniques

    * Interactive environments, such as siege towers and fortified battlements

    * Thousands of new weapons, armor, and magical items, including class-specific quest items

    * New recipes for the Horadric Cube

    * Increased Stash Size

    * Supports 800x600 Resolution

Source: http://www.blizzard.com/us/diablo2exp/