Winchester Draft is a casual limited Magic: The Gathering format that combines rules of Rochester Draft and Winston Draft formats.  
Like in Winston, all supplied products are put into one large stack and separated into smaller piles with one card each at the beginning. Usually four piles are used. These piles are face up and the cards in the pile are known. The first player must choose a pile. Then one card from the stack is added to each pile, meaning the chosen pile is now one card while all other piles are two cards. Players take turns taking piles in this manner until the stack is used up.
Each player then builds a 40 card limited deck using any number of basic lands.