In this expansion, you aren't just racing through the dungeon anymore, you are also dealing with corruption. If you aren't participating in the dungeon, you are seen to the rest of the world as corrupt. Now, you'll be losing resources between turns if you are corrupted, however, you'll gain benefits for being a certain amount of corrupt. Who knew being bad can be so good?
You'll also have Leader cards to choose from in the beginning of the game. These will give the players a special ability as well as a player specified quest they can complete. This gives players more of a focus at the start of the game.
There are also a ton of new Adventure and Hero cards that may activate when you reach a certain amount of corruption.
-description from publisher's website