Posting on their blog, Blizzard has detailed some of the changes that Patch 2.4 will bring to the table. Most notable would be the inclusion of a new zone called the Greyhollow Island. According to Blizzard’s description, “Explore a new stretch of Sanctuary by venturing to Greyhollow Island! This mysterious forested locale is steeped in intrigue, and rumors abound that those who visit are doomed to never return. Brave the wild beasts and supernatural creatures and unravel the mystery behind the tragedies that have occurred here.”
In addition to Greyhollow Island, Blizzard has also announced that they will be expanding two zones from The Eternal Woods and the Royal Quarters, giving players more lore and areas that they can explore in the game. There is also a new mode called Set Dungeon. Basically this is for players who have collected all six pieces of their armor set.
When they do, they will be able to take part in a dungeon that has been designed specifically for their set (and the bonuses). Along with the new dungeon, there will also be Empowered Rift, new Legendaries, and more. Note that the patch has yet to make it onto the PTR meaning that there is a very good chance some of these features could change ahead of its release, but for now it sounds pretty good.