Book Of Vile Darkness by Wizards of the Coast

A controversial Dungeons & Dragons supplement that examines extreme evil in explicit detail, offering lore, mechanics, and guidance for dark-themed play; it provides new spells, magic items, monsters, prestige classes, feats, rituals and artifacts tailored to villains and depraved cults, plus rules for corruption, moral consequences, and running mature, morally fraught campaigns. The book balances game mechanics with lurid examples and scenario advice intended to help Dungeon Masters create memorable antagonists, horrific locations, and morally challenging encounters while emphasizing the narrative and mechanical impact of embracing evil.