Sorry they are messy at the moment. I am having a hard time finding a good copy of the rules. If anybody comes across a well edited version please let me know.
Two-Headed Giant games are played with two teams of two players each. No other multiplayer options are used in Two-Headed Giant games. Each team sits together on one side of the table. Each team decides the order in which its players sit. The player seated on the right within each team is the primary player, and the player seated on the left is the secondary player. The Two-Headed Giant variant has two unique features: Each team has a shared life total, which starts at 40 life. Each team takes turns rather than each player. With the exception of life total, a team’s resources (cards in hand, mana, and so on) are not shared in the Two-Headed Giant variant. Teammates may review each other’s hands and discuss strategies at any time. Teammates can’t manipulate each other’s cards or permanents. A player who is dissatisfied with his or her initial hand may mulligan. First, the starting team takes any mulligans. For a team to take a mulligan, each player on that team decides whether to shuffle his or her hand back into the deck and then draw a new hand of seven cards. All players on that team who chose to do so take their mulligans at the same time. After each player on that team who took a mulligan looks at his or her new hand, the team repeats the process, resulting in a hand of one fewer card each time, until the hand size reaches zero cards. Teammates may consult during this process, but a player can’t see the result of his or her teammate’s mulligan before deciding whether to take a mulligan at the same time. Once a player has decided to keep a hand, those cards become his or her opening hand. That player can’t take any more mulligans, but his or her teammate may. Once each player on the starting team decides to keep an opening hand, the other team may take mulligans. During the draw step of the starting team’s first turn, only the secondary player draws a card. The primary player does not. Teams have priority, not individual players. The Active Player, Nonactive Player order rule is modified for Two-Headed Giant play. The team whose turn it is is the active team. The other team is the nonactive team. If both teams would make choices and/or take actions at the same time, first the active team makes any choices required, then the nonactive team makes any choices required. Then the actions happen simultaneously. A player may play a spell or activated ability, or take a special action, only when his or her team has priority. If both players on a team want to take an action at the same time, the primary player decides who takes the action. Each player on a team draws a card during that team’s draw step. Each player on a team may play a land during each of that team’s turns. If neither player on a team wishes to do anything, that team passes. If both teams pass in succession (that is, if both teams pass without any player taking any actions in between passing), the top object on the stack resolves, then the active team receives priority. If the stack is empty when both teams pass in succession, the phase or step ends and the next one begins. If an effect gives a player an extra turn or adds a phase or step to that player’s turn, that player’s team takes the extra turn, phase, or step. If an effect causes a player to skip a step, phase, or turn, that player’s team does so. If an effect causes a player to control another player’s turn, the controller of that effect controls the affected player’s team’s turn. If an effect instructs more than one player to draw cards in a Two-Headed Giant game, first the primary player on the active team performs all of his or her draws, then the secondary player on that team performs all of his or her draws, then the nonactive team does the same. The Two-Headed Giant variant uses different combat rules than other multiplayer variants: Each team’s creatures attack the other team as a group. During the combat phase, the active team is the attacking team and each player on the active team is an attacking player. Likewise, the nonactive team is the defending team and each player on the nonactive team is a defending player. As the declare attackers step begins, the active team declares attackers. If a creature is unable to attack one of the defending players, that creature can’t attack the defending team. The active team has one combined attack, and that set of attacking creatures must be legal as a whole. Example: One player in a Two-Headed Giant game controls Teferi’s Moat, which says “As Teferi’s Moat comes into play, choose a color. / Creatures of the chosen color without flying can’t attack you.” Creatures of the chosen color without flying can’t attack that player’s team. As the declare blockers step begins, the defending team declares blockers. Creatures controlled by the defending players can block any attacking creatures. The defending team has one combined block, and that set of blocking creatures must be legal as a whole. Example: If an attacking creature has forestwalk and either player on the defending team controls a Forest, the creature can’t be blocked. As the combat damage step begins, the active team announces how each attacking creature will assign its combat damage. If an attacking creature would assign combat damage to the defending team, the active team chooses only one of the defending players for that creature to assign its combat damage to. Then the defending team announces how each blocking creature will assign its combat damage. The Two-Headed Giant variant uses the normal rules for winning or losing the game with the following additions: If a team’s life total is 0 or less, the team loses the game the next time a team would receive priority.
Players win and lose the game only as a team, not as individuals. If either player on a team loses the game, the team loses the game. If either player on a team wins the game, the entire team wins the game. If an effect would prevent a player from winning the game, that player’s team can’t win the game. If an effect would prevent a player from losing the game, that player’s team can’t lose the game. Example: In a Two-Headed Giant game, a player controls Transcendence, which reads, in part, “You don’t lose the game for having 0 or less life.” If that player’s team’s life total is 0 or less, that team doesn’t lose the game. Example: In a Two-Headed Giant game, a player attempts to draw a card while there are no cards in that player’s library. That player loses the game, so that player’s entire team loses the game. Example: In a Two-Headed Giant game, a player controls Platinum Angel, which reads, “You can’t lose the game and your opponents can’t win the game.” Neither that player nor his or her teammate can lose the game while Platinum Angel is in play, and neither player on the opposing team can win the game. If a player concedes, his or her team loses the game. Damage, loss of life, and gaining life happen to each player individually. The result is applied to the team’s shared life total. Example: In a Two-Headed Giant game, a player plays Flame Rift, which reads, “Flame Rift deals 4 damage to each player.” Each team is dealt a total of 8 damage. If an effect needs to know the value of an individual player’s life total, that effect uses the team’s life total divided by two, rounded up, instead. Example: In a Two-Headed Giant game, a team is at 17 life when a player activates Heartless Hidetsugu’s ability, which reads, “Heartless Hidetsugu deals to each player damage equal to half that player’s life total, rounded down.” For the purposes of this ability, each player on that team is considered to be at 9 life. Heartless Hidetsugu deals 4 damage to each of those players, for a total of 8 damage. The team will end up at 9 life. Example: In a Two-Headed Giant game, a player controls Test of Endurance, an enchantment that reads, “At the beginning of your upkeep, if you have 50 or more life, you win the game.” At the beginning of your upkeep, the player’s team wins the game only if his or her share of the team’s life total is 50 or more. The team’s life total must be 99 or more for that to happen. Example: In a Two-Headed Giant game, a player controls Lurking Jackals, which reads, “When an opponent has 10 life or less, if Lurking Jackals is an enchantment, it becomes a 3/2 Hound creature.” If the opposing team has 22 life and 1 damage to a particular opponent, Lurking Jackals won’t become a creature. The opposing team’s life total must be 20 or less for that to happen. If an effect would set the life total of each player on a team to a number, the result is the sum of all the numbers. Example: In a Two-Headed Giant game, a player plays Biorhythm, which reads, “Each player’s life total becomes the number of creatures he or she controls.” If one member of a team controls three creatures and the other member controls four creatures, that team’s life total becomes 7. If an effect would set a single player’s life total to a number, that player’s individual life total becomes that number. The team’s life total is adjusted by the amount that player's life total was adjusted. Example: In a Two-Headed Giant game, a player on a team that has 25 life plays a spell that reads, “Your life total becomes 20.” That player’s life total is considered to be 13 for the purpose of the spell, so it becomes 20 and the team’s life total becomes 32 (25 + (20 - 13)). The Two-Headed Giant variant can also be played with equally sized teams of more than two players. Each team’s starting life total is equal to 20 times the number of players on the team. (These variants are unofficially called Three-Headed Giant, Four- Headed Giant, and so on.)