From publisher blurb:
Smooth talking has been a staple of fantasy settings since the days of Tolkien. And now, you can add a truly sinister master manipulator to your game! Dark Whisperers are masters of guile and cunning. Consumate flatterers, liars, and manipulators, the Dark Whisperer dominates realms and steers kingdoms. And does it all with a few well placed words and suggestions. The mask he wears enables him to slide unnoticed through any crowd, to better his rise to power.
Ancient Lore I - Dark Whisperer details the Dark Whisperer prestige class. This class has 5 levels, and prerequisites include levels as an arcane spell caster.