Angered by his previous failures to destroy the small groups of adventurers that stood in his way, Diablo has reincarnated himself once again at his absolute maximum strength. The demonic ritual which caused this ultimate reincarnation was long thought to be impossible, even by the most learned arcane scholars. Now, the Lord of Terror sets his plan in motion, and he and his brothers will unleash a new wave of Pandemonium upon the world of Sanctuary...
Pandemonium Diablo lies in a secret realm where, together with his brothers, he commands three generals. These generals, Lilith, Duriel, and Izual, conduct operations from their own hidden realms. Adventurers powerful and clever enough to unravel the secrets behind this "Pandemonium" will obtain knowledge and treasure used only by the most powerful agents of sin.
- Arreat Summit