From their website:
Fantasy Flight Games is pleased to announce the upcoming release of Descent: Journeys in the Dark Second Edition! This updated version of the classic board game of dungeon-delving adventure features a host of enhancements, including new heroes and monsters, streamlined rules, a class-based hero system, campaign play, and much more.
Descent: Journeys in the Dark Second Edition features eight never-before-seen heroes, ready to face off against nearly forty all-new monsters in nine distinct types. And with Second Edition’s enhanced experience system, you’ll have total control over your character’s growth and development. As you gain more experience throughout the included campaign, you’ll be able to periodically spend it on additional skills, adding to your hero’s available abilities. This, along with an innovative character selection system, lets you experience the dangers of Terrinoth like never before.