this is a geniune spell that i had acquired from a crone witch:
First, may sound weird but whole milk. Just a cup. Exactly. No more no less. Next, grab a teaspoon of both pepper and horseradish sauce and mix it. Make it a little warm by warming it up over an open fire or on a stove. Lastly write down the name of the person you want to switch souls with and put it in the drink. Drink it all, and you should feel it work in 4-5 days. These potions take time.
(let me know if anything happened, i haven't got the ingredients yet but i will tommorrow.)