Chaos Draft is just like any other Magic Draft format: get together with seven of your best drafting buddies and grab three packs of cards for each drafter. The twist is that instead of drafting a normal format—two packs of Oath of the Gatewatch and a pack of Battle for Zendikar, or three packs of Magic Origins, or any of those other carefully crafted formats—you cobble together as many different packs from different sets as you can scrounge up and distribute them randomly among your players.