Diablo 3's Reaper of Souls expansion will see the addition of a new Artisan, Myriam Jahzia, the Mystic. She'll aid players in their quest to keep the forces of Hell at bay by Enchanting and Transmogrifying their items, Blizzard explained in a post that reintroduces the Mystic.
Enchanting in Reaper of Souls allows players to re-roll one of the properties of a rare or legendary class item for another, possibly better random property. Players are required to pay a gold and material cost to complete the Enchanting process, but the Mystic's skills will likely pay off for players looking to tweak an item that's not perfectly suited to their needs.
Transmogrifying an item in Diablo 3: Reaper of Souls lets players alter the appearance of that item without sacrificing its properties. Players who prefer the look of a particular armor item, for example, can visit the Mystic and pay in gold to change its style, leading to better dressed heroes. There are some restrictions and rules that govern Transmogrifying in Reaper of Souls, which Blizzard details at the official Diablo 3 site.
The Mystic was originally planned to appear in Diablo 3, but the developer removed her from the game after determining that her function was redundant in the game's customization system.
Diablo 3: Reaper of Souls is scheduled for release in 2014 on PC and PlayStation 4.