That means killing monsters elites and bosses opening chests gambling at kadala and upgrading rare items at the cube.
Diablo 3 materials farming.
Home diablo 3 farming how to farm legendary and set items.
Staff of herding hellfire amulet hellfire ring etc.
Like the vast majority of items in diablo 3 legendaries and set items can only be found through chance and cannot be target farmed.
Crafting materials crafting artisans require an array of materials recovered from the wilderness to craft their wares.