Open these packs:
You open these packs in a team of two, and they are what your team gets between the two of you. From the cards you open and any number of basic land cards, each of you builds their own 40 card deck. Cards you don't use are a shared sideboard.
Games are played as Two-Headed Giant: two teams of two players, each team sharing a life total of 30 and taking their turns together. See rule 810 for the full rules.