Information from Fantasy Flight Games website:
An Ancient Threat Rears Its Head Once More ...
Deep in the bowels of the world, there lies a chasm that was sealed over a millenium ago. Within it lies a force of evil so great that, were it to be unleashed, it would plunge the world into a thousand years of darkness.
Before you can face that challenge, however, you'll battle your way through dank tunnels, trapped temples, and even volcanoes to prove your worth. You'll face a host of new tricks, traps, and other lethal obstacles over the course of your quest, including scything blades, rolling boulders, and boiling hot lava.
Descent: the Well of Darkness features six new heroes, tricky kobolds, bloodsucking ferrox, and unstoppable golems. Heroes will find more skill and treasures at their disposal, including six new relics and a new type of potion. The Overlord, on the other hand, gains the ability to customize his deck before every game, putting in devastating new trap, event, and spawn cards.

Descent: the Well of Darkness includes:

� Over 30 plastic models, including 3 new monster types and six new heroes!
� New traps, including scything blades, dart fields, lightning bolts, and the dreaded giant boulder!
� New hero abilities of all sorts, including a new familiar!
� Brand new quests, more dangerous than can be believed!
� Six new relics!
� A new type of potion!
� New customizable Overlord deck rules make the evil more treacherous than ever before!
� New treasures!
� More dungeon tiles make for even larger dungeons!
� Nine new quests with never-before-seen peril!