The Mystic re-enchants weapons and armor. The basic idea is this: you have an awesome sword for your Barbarian but it has a useless Intelligence roll on it. You can take it to the mystic, pick that roll, and she'll re-roll it to something else. Now, it wouldn't be Diablo if you could pick that roll, there has to be some chance thrown in. So of course, the re-roll may be worse than what you started with, and in this case you can choose to stick with the...

I really like this addition considering the removal of the auction house. I do have one question though, is this coming to Reaper only or the main game?
Not really that it matters to me much, I am getting Reaper day one anyways :D