Use the Rotten Mushroom on the cauldron back in Old Tristram to get the Witch's Brew.Fight to level 9 of the old dungeon, find the black mushroom cluster and acquire the Rotten Mushroom.Here's the whole process in bullet point cheat sheet form: If you click on the dead cows in that order then, according to players who followed this process in the PTR build of the update, you'll gain access to a farm area that contains a chest, which in turn contains a bovine pet. 2, 1, 3 should correspond to middle, left, then right. Head back to the cauldron and prod the cows. Luckily I warned you against doing this like ten times, so you're hopefully good to go. Remember the cows near the cauldron? I have not been able to test this part, because I foolishly prodded all the cows when I first explored the area, bringing their spirits back in the wrong order.