Witch's Brew is an Item in Diablo 3: The Darkening of Tristram
Description
This strange concoction has been steeping for several years now...
Acquisition
Head out of Tristram to the Northeast. Take the First turn to the Southeast. This will lead you to Adria's Hut.
Inside it is the Cauldron. Head over to it and interact with it. This will cause it to drop Witch's Brew. Head back to Tristam