Players choose a legendary creature as the "Commander" for their deck.

Players may choose any legendary creature as their Commander, although some choices may be met with disapproval by other players. Two players in the same game may choose the same Commander, and other players may include that card in their Deck even if it's not their Commander. Commanders are subject to the Legend rule just like any other legendary creature. The Commander is the principle around which the deck is built. It is more easily available than other cards in the deck, and decks will ususally want to leverage their Commander's strengths in their plans. A deck's commander is also known as its "General" for historical reasons.

A card's colour identity is its colour plus the colour of any mana symbols in the card's rules text. A card's colour identity is established before the game begins, and cannot be changed by game effects.

Lands whose type includes swamp, island, plains, forest and/or mountain (e.g.: basic lands, shocklands, dual lands, Shadowmoor special-basics, etc) also have the corresponding colour identity. As such, they may not appear in a deck unless the Commander is also of the appropriate identity. While hybrid mana symbols may be played with either colour mana, they contribute both colours to the card's colour identity. Therefore they may only be played with a Commander whose identity includes ALL of the hybrid symbols' colours. Basic land words (swamp, forest, etc) in the text box of a card do NOT represent a coloured mana symbol. They are not restricted to a Commander of the same colour identity. Reminder text is not included in the colour identity of a card. The back face of a double-faced card is included when determining a card's colour identity. Cards in a deck may not have any colours in their color identity which are not shared with the commander of the deck. (The identity of each card in the deck must be a subset of the Commander's) Examples A deck with Phelddagrif (Casting cost 1UWG) as the Commander may not contain any cards whose colour identity includes red or black. These cards would all be illegal in a Phelddagrif deck: Goblin Piker (Its mana cost contains a red mana symbol) Elves of Deep Shadow (Its ability contains a black mana symbol) Talisman of Dominance (All sorts of verbotten mana symbols) Life//Death (Three shall be the number of the colours) Degavolver (... right out) Our Phelddagrif couldn't use any of these lands: Underground River (Obvious, see above) Godless Shrine Badlands Leechridden Swamp, etc) Phelddagrif may not call upon Boros Guildmage for help Phelddagrif IS allowed to use: Esper Panorama Shard Convergence.

A Commander deck must contain exactly 100 cards, including the Commander.
Starting Hand Size Rule
  • Players start each with seven (7) cards in hand. But in case you choose to start with more than one commander by playing two (2) cards with the partner ability the starting hand size changes as following:

    • If a player uses partner commanders then he or she draws seven (7) cards and puts X cards in the bottom of their library in any order, where X is 1 plus the number of mulligans taken.

  • This way if players start the game with two (2) commanders and choose to take no mulligans, X will be one (1) and the player will have to put a single card from their hand on the bottom of their library. If they choose to mulligan once the number of cards put on the bottom of their library will be two (2) and so on in the same way for more mulligans.

With the exception of basic lands, no two cards in the deck may have the same english name. Some cards (e.g. Relentless Rats) may have rules text that overrides this restriction.
Players begin the game with 30 life.
Commanders begin the game in the Command Zone. While a Commander is in the command zone, it may be cast, subject to the normal timing restrictions for casting creatures. Its owner must pay {2} for each time it was previously cast from the command zone; this is an additional cost.
If a commander is in a graveyard or in exile and that card was put into that zone since the last time state-based actions were checked, its owner may put it into the command zone. If a commander would be put into its owner’s hand or library from anywhere, its owner may put it into the command zone instead. This replacement effect may apply more than once to the same event.
Being a Commander is not a characteristic [MTG CR109.3], it is a property of the card and tied directly to the physical card. As such, "Commander-ness" cannot be copied or overwritten by continuous effects. The card retains it's commanderness through any status changes, and is still a commander even when controlled by another player.
If a player has been dealt 21 points of combat damage by a particular Commander during the game, that player loses a game.

This is an additional state based effect. Commander Damage is cumulative throughout the game; nothing can reduce the amount of damage a Commander has previously done to a player. Because it is a property of the card and not a characteristic of the game object, a card is still the same Commander even if it leaves the field and returns. While effects can raise a player's life total, it doesn't reduce the amount of damage previously taken from a Commander. (eg: Beacon of Immortality) Conversely, combat damage can be reduced, prevented, or replaced as it is taken, in which case it was never dealt and doesn't count towards the total taken from that Commander. (eg: Fog or Captain's Maneuver) Commander Damage is specific to each Commander/Player pairing, not combined across all Commanders. A player can lose if he or she is dealt 21 points of combat damage by his or her own Commander (ie: under someone else's control).

Commanders are subject to the Legend rule; a player cannot control more than one legend with the same name.
Commander Swap Rules
  • After each game players decide if they want to keep using the same commander or swap for another.

  • Players decide at the same time not knowing if their opponent is choosing to change or not. Each player shuffle his or her commander(s) into his or her deck and present either the same one(s) or new commander(s) from the same deck before each following game begins during each round.To ensure the information is not revealed both players place their commander face down and flip them up as the next game starts.

  • If you choose to swap, your previous commander is shuffled into your library. The color identity of your deck has to remain the same. For Example: If you start with a Dragonlord Ojutai (UW) as your commander, you can only swap to other commanders with UW identity, making Geist of Saint Traft a legal option and Vendilion Clique (U) illegal.

  • Players cannot swap to commanders that are on the Banned as Commander List.

  • Players are allowed to swap from a single commander to having two in the case of partners and vice-versa.

Abilities which bring other card(s) you own from outside the game into the game (such as Living Wish; Spawnsire of Ulamog; Karn, the Great Creator) do not function in Commander.
The required minimum time limit for any match is 45 minutes. 

The following time limits are recommended for each round of a tournament:

  • Swiss rounds - 50-55 minutes

  • Single-elimination quarterfinal or semifinal matche - 90 minutes

  • Single - elimination final matches - no time limit

Get fun!

and more fun!! ;)