Dungeons & Dragons: Adventures in the Forgotten Realms is an exciting set that ventured into . . . well, it ventured into a lot of new mechanical space with Classes, dungeons, and rolling d20s. This also means a lot of shiny new rules were added to cover these mechanics. There were also a few rules changes with this set, and there were a few changes to the Oracle text of some Magic cards, including adding the Ranger and Bard creature types to some older Magic cards.
Both the rules changes and Oracle changes are still under review, so it's possible they'll be a little different from the final changes. When they're finalized, you'll be able to see them on the rules page and Gatherer.
Alright—let's venture in!
Comprehensive Rules Changes