Pie Ale is an ale only sold by Sark the Merchant, and is apparently ale made of pie. The exact recipe for creating pie ale is a well-kept secret by Sark. Although Sark claims it's completely unrelated and coincidental, pie ale seems to polymorph anyone who drinks it into the shape of other creatures for a few minutes. With Sark having moved from Frostkeep, he longer seems to sell pie ale - not openly anyway.