So I know that there are multiple levels of the Staff of Herding, and they get significantly more expensive as you go up in difficulties. I play with a lot of people who have varying amounts of time to play, and will be at vastly different levels. I'd like to be able to go into the unicorn level with anyone, no matter what level they are.
Will I need to get a staff for each level if I want to be able to enter Whimsyshire on multiple difficulties, or will an Inferno Staff open all the lower level portals?