It can be accessed through the following steps (Note: as they have become account bound, these items cannot be collected from various players):
- Step 1 (Acquire all items)
- Black Mushroom, which spawns on the first level of Tristram Cathedral in Act 1.
- Leoric's Shinbone which is located randomly in the fireplace in Leoric's Manor in Act 1.
- Liquid Rainbow is found in a Mysterious Cave within Dahlgur Oasis. The cave is opened by Zaven the Alchemist after he has been saved from a pack of Deathly Haunts. The item is located within a Mysterious Chest. Neither Zaven nor the chest are guaranteed to appear.
- Wirt's Bell is sold by Squirt the Peddler in Caldeum Bazaar or Hidden Camp (rare) in Act 2 for 100,000 gold. May not always be available for sale.
- Gibbering Gemstone, dropped by Chiltara in level 2 of the Caverns of Frost in Act 3.
- Plans: Staff of Herding, dropped randomly by Izual or Diablo in Act 4.
- Step 2 (Build Staff of Herding)
- Teach Haedrig how to build the staff. The recipe includes all of the items mentioned previously, plus a one-time cost of 50,000 gold.
- Step 3 (Talk to the Ghost of the Cow King)
- Put the Staff of Herding in your inventory (it's not necessary to equip it). Note that the staff is permanent and it is not consumed; in fact, you can replay the Whimsyshire level as many times as you like.
- If necessary change quest and select Act I (e.g. "A Shattered Crown" or later).
- Take The Old Ruins waypoint (Act I) and head west down Old Tristram Road, hugging the south wall. There should be a Skeletal Corpse (resembling a cow) and a "rift" in one of the crevices in the ground. If you have the Staff, the Ghost of the Cow King will appear with a quest above his head. Once finished click on the rift which should be now glowing red, blue, yellow, etc. (rainbow colors), to enter Whimsyshire.
- The difficulty of Whimsyshire is one notch higher than the campaign you are playing; e.g. if you are playing the normal campaign expect Whimsyshire difficulty to be almost nightmare.
Higher difficulty levels
To access Whimsyshire on higher difficulties (nightmare, hell, inferno), the Staff of Herding must be upgraded. To do so, plans must be acquired from the quartermaster near your followers in Bastion's Keep in Act IV for 1 gold. (Please note that now the plans cost also 20,000) But you must defeat Izual on that difficulty before the merchant will sell it (i.e. kill Izual on Nightmare to purchase the Nightmare plan). Only the previous Staff of Herding is required to craft the newer staff, but it costs a substantial amount of gold (200,000 for nightmare, 500,000 for hell and 1,000,000 for inferno). Once you have upgraded your staff it can still be used to access the lower difficulties.
Once upgraded, the name of the staff will change. Names for specific difficulties:
Normal: Staff of Herding
Nightmare: Nightmarish Staff of Herding
- Requires that you are on the Diablo Quest on Nightmare difficulty.
Hell: Hellish Staff of Herding
- Requires that you are on the Diablo Quest on Hell difficulty before buying the plans.
Inferno: Infernal Staff of Herding
- Requires you to be level 60.
- Requires that you are on the Diablo Quest on Inferno difficulty before buying the plans.