For the Great Evil, see Azmodan.
Azmodan, the Lord of Sin is a tome found in Act II of Diablo III.
It is found in one of Cain's Lost Satchels. Reading it adds to the Judge of Character achievement.
It reads as follows:
The Valrous manuscript lists Azmodan as the best battlefield commander of all demons, having defeated the angels many times in the Eternal Conflict across Pandemonium and the Prime Evils in the demonic civil war. If the Lord of Sin ever assaults our realm, we truly have much to fear. — Deckard Cain