After the Cow King's ghost conversation, the pit glow changes to a rainbow color and it becomes a clickable dungeon entrance. As was the case with the Diablo II secret cow level, characters must have defeated that difficulty level to enter the secret level, which is balanced to be about as difficult as Act 4.

Required Ingredients: Black Mushroom -- Found rarely in a room on Cathedral level one, in early Act One. It's a clickable ground spawn called Black Mushrooms and does not always spawn. One way to farm for this is to load a later quest in Act I and take the Cathedral Gardens Waypoint then proceed through Leoric's Passage to Cathedral Level

Leoric's Shinbone -- Found rarely in the fireplace in Leoric's Manor, in late Act One. However it does not appear in every game because the burnt logs don't always spawn. The item is obtained by clicking the burnt logs in the fire place within Leoric's Manor which drop the shinbone 100% of the time. The easiest way to get to Leoric's Manor is to enter Act I on quest 9-The Imprisoned Angel and using the Leoric's Manor Waypoint.

Wirt's Cowbell -- Wirt's Bell can be purchased from Squirt the Peddler in the Caldeum Bazaar (Act 2). It is under the miscellaneous tab.

Liquid Rainbow -- Spawns in the Mysterious Cave in the Mysterious Chest in the Oasis, Act 2. Save the old man and he will open the chest.

Gibbering Gemstone -- Random drop from Chiltara in the Caverns of Frost, Act 3. It's in the Ballistae fight area. If you get Ice Caverns exit out try again. The mob is random.

Plan: Staff of Herding -- To teach the recipe to Haedrig the blacksmith. Drops randomly from Izual, Act 4.