From the publisher's website:

"The Portals Expansion adds a ton of new features that all the fans have been asking for in regards to player interaction. With Portals players can now trade, do battle, and even hire thieves to steal from one another.

Portals also introduces Mystical Forces to the game, magical energies that can be a boon or a bane to all players.

- Trade and do battle with your opponents
- Hire thieves to pilfer treasure
- Take advantage of magical random effect cards
- Escape deadly new traps
- Acquire powerful treasures -- the Scroll of Life Stealing and the Divine Statue await!
- Portals also includes 1 new hero -- designed by a player like you!"