Partners share turns and life totals. The starting life total for most formats is 30. Additional rules are format dependent.
Great for a family event or "bring-a-friend" night. New players tend to enjoy this format as it allows them to play alongside someone they know.
Limited: A team shares a sideboard which consists of all the cards from their pool that were not put into the team's main decks.
Constructed: A team's combined decks may not contain more than four of any individual card (with the exception of basic lands).
Limited: There is no limit to number of individual cards that can be played. Example: Having 5 or more of an individual card is permitted.
See this page for a list banned cards.