Teams must choose 2 different Clans but may share their cards when building.
For Tarkir: Dragonstorm there are five different versions of the Prerelease Pack, one for each clan of Tarkir. Players will be allowed to choose their own clan from what options are available. For the two-headed event, each teammate will be asked to choose two different clans in total. (Both Players on one team can not play the same clan.)
When you register for one of these events, you'll receive a Prerelease Pack containing the following:
5 Tarkir: Dragonstorm Play Boosters 1 Clan-themed Tarkir: Dragonstorm Prerelease Booster Includes 14 Magic: The Gathering cards Each contains 1 of 9 rares (66.7%) or mythic rares (33.3%) tied to the Prerelease Pack's clan. 1 Traditional foil year-stamped rare or mythic rare card This card is not tied to the Prerelease Pack's clan. 1 Deck box 1 Spindown die (matches the Prerelease Pack's clan)