You can use it over and over again to open Whimsyshire repeatedly. It goes away when sacrificed at the altar, of course, so it's worth it to use it first just for the fun of it before sacrificing it. Not to be confused with a Bovine Bardiche, which is consumed when used at the cube. How do you use it?
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. Whimsyshire can be accessed in both Adventure and story mode.
Once you've got a Staff of Herding in your inventory, head to the Act 1 camp and then portal over to The Old Ruins waypoint. From here, head west but keep hugging the southern-most part of the screen. Eventually you'll reach a glowing chasm in the ground, with a spectral cow standing nearby.
The Plans: Staff of Herding are a required ingredient to craft the Staff of Herding, which is used to gain access to Whimsyshire. 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.
When she spawns, she has a rare chance to drop the Gibbering Gemstone. The item will be account bound as soon as it drops. There is also a bounty quest to kill Chiltara, which may make finding the Huntress easier. Gemstone drop rate is approximately 5%, but as of patch 2.0.
What difficulty level are you farming it on? Keep in mind that a while back, Blizz made all mats, including Gibbering Gemstone, a higher droprate on higher torment levels. So if you are speed running normal, or even low torments for it, you should just instead do T16 runs for it.
The Black Mushroom is a reagent for the Staff of Herding which grants you access to the secret level Whimsyshire. This item is found in the Cathedral Level 1 in Act I. It doesn't always spawn but if you want to farm for it, take the Waypoint to Cathedral Level 1. Simply explore that level, rinse and repeat.
I think the drop rate is somewhere between 2% and 5% (without MF). Here is an important Note: The "Plan: Staff of Herding" is a legendary item and thus it is affected by Magic Find. If you have a very high MF > 300 % you will get the Plan very often.
The Black Mushroom is an item used to craft the Staff of Herding, which can be used to gain access to Whimsyshire. It can be found on Level 1 in the Cathedral (Normal difficulty).
Wirt's Bell is a miscellaneous crafting material in Diablo III, it is used to construct the Staff of Herding which is necessary to access Whimsyshire. It has an Item Level of 1 and requires a character level of 1.
Can be found in Adventure Mode and is made easier to gather when the Bounty in Dahlgur Oasis is for clearing the Mysterious Cave Level 2 of all enemies.
The Nightmarish Staff of Herding was a craftable staff in Diablo III. It was needed to access Whimsyshire on Nightmare difficulty. As of version 2.0, any version of the Staff of Herding will grant the player access to Whimsyshire on any difficulty, so it is no longer necessary nor possible to upgrade the staff.
Whimsyshire is a Secret Level, or secret land, in Diablo 3. When you enter the Secret Level of Whimsyshire a Feat of Strength along with a Banner and Sigil are unlocked. You can run the Whimsyshire level as many times as you want and you will get the In The Land Of Killer Unicorns achievement for finding it.
Whimsydale is a unique location in Diablo III that can only be accessed by killing a Rainbow Goblin. It uses the Whimsyshire tileset, and is overall identical to it. This location was added in patch 2.1.
While Whimsyshire most exists for the portrait frame and the sense of accomplishment, getting to go to Whimsydale means lots of gold, crafting materials and gemstones. It rivals the Realm of Greed in terms of pure financial reward and loot to be on offer.
Leoric's Shinbone is a miscellaneous crafting material in Diablo III, it is used to construct the Staff of Herding which is necessary to access Whimsyshire. It can sometimes be found in the fireplace of Leoric's Manor in Act I.
The drop rates are roughly a 5% chance from a Pinata (Hamburger) and a 10% chance for a Spectrum from any unique (read: purple named) mob. It can be a long time before you find one, but certainly can be rewarding.
Its role is to isolate and protect the developing spore-producing surface, represented by gills or tubes, found on the lower surface of the cap. A partial veil, in contrast to a universal veil, extends from the stem surface to the cap edge.
Mother spawn is nothing but the mushroom fungus grown on a grain based medium. Among the several substrate materials tested by TNAU, Coimbatore, sorghum grains are the best substrate for excellent growth of the fungus. Disease- free sorghum grains are used as substrate for growing the spawn materials.
Zuggtmoy or Tsuggtmoy was the Demon Queen of Fungi. Her symbol was a jawless human skull with fungi blooming from within, though some of her false cults used other symbols. For example, her cult in the Temple of Elemental Evil used the symbol of the Elder Elemental Eye.
Torment XIII requires GR 60. Torment XIV requires GR 65. Torment XV requires GR 70. Torment XVI requires GR 75.
So your character level and class determines what kadala can give you, but once you get to 70 she can give you all items in your class drop pool. Paragon level is irrelevant, as is game difficulty level afaik. Kadala scales inversely.