The Normal version (and only the Normal version) of the plans are dropped randomly by Izual on Act 4: Prime Evil (on any difficulty level). Head to The Crystal Colonnade and find your way to the Gateway to the Silver Spire. Next you will enter the Silver Spire Level 1, and finally encounter Izual on The Great Span.
- Note: The plans are not a guaranteed drop.
- Plans are now considered Legendary, Magic-Find will help.
The other versions of the staff require a separate recipe, which can be purchased from Gorell the Quartermaster in town in Act 4. To buy the recipe, you must be on the quest to kill Diablo, on the proper difficulty setting: that is, to give an example, the Nightmarish Staff of Herding recipe can only be bought on Nightmare. While the recipes can be bought for 20,000 for the Nightmarish Staff Plans, Hellish Staff Plans 50,000, and Infernal Staff Plans 100,000 (after newest patch1.03), crafting the staff is quite expensive at 200,000 gold for the Nightmarish Staff of Herding, 500,000 gold for the Hellish Staff of Herding, and 1,000,000 gold for the Infernal Staff of Herding. Fortunately, you do not need to obtain the many items found throughout the acts as with the first version of the staff - you just upgrade the previous staff with a fixed amount of gold.