“With the Dark Origins update we’re making some changes to modernize the Daily Challenge system. Older dungeons are being removed from the rotation and replaced with more recent ones. You’ll also now only have to complete three Daily Challenges per day to get the reward (out of the six available), and the reward when you do complete them has been improved and gold amount increased.”
NCsoft’s also noted that the previously announced server merges have been completed. Check out the whole patch notes for a run-down of the class changes and then take a peek at the brand-new trailer.
Source: Official site