You get in there by making a staff of herding. People have found the plans from bosses in act4. The Mushrooms are in the crypts/cathedral. Leoric's Shinbone is in the Manor. Most people are reporting it being next to the fireplace will confirm when I can get back in. Liquid Rainbow is in the oasis. I got it from a dungeon next to a merchant. Gibbering Gemstone I still have no clue about. Wirt's Bell is 100,000 in Caldeum. Plans of Staff of Herding. (50,000 crafting cost) The idea is that once you make the staff you have to then go back and refind the items to make it again, to reach higher difficulties of the level you have to have the higher level of plans. Nightmarish Staff of Herding. Drops in Nightmare difficulty. (200,000 crafting cost) Hellish Staff of Herding. Drops in Hell difficulty. (500,000 crafting cost) Infernal Staff of Herding. Drops in Inferno. (1,000,000 crafting cost) So 1.75million to make the infernal version of the staff.