A blacksmith, mystic and jeweller will be discovered during the action RPG's main quest and essentially take over the crafting, socketing and combining duties of Diablo II's Horadric Cube. In true Diablo style, most items they create will have some random properties.
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If you're worried about your inventory filling up now your Horadric Cube's walking around on legs, you'll be relieved to know in Diablo 3 you can salvage items in the field to produce raw crafting materials for the artisans to work into wonders. Artisans can be taught new crafting recipes by upgrading them, plus some recipes are dropped as loot.
There's still no word on a release date for Diablo 3.