RULES

Deck Construction Rules (Summary)

(From https://mtgcommander.net/index.php/rules/)
WARNING : For complete rules, check these websites :
French Commander
Leviathan Commander
Archon Commander
Brawl

  1. Players choose a legendary creature as the commander for their deck. 
  2. A card’s colour identity is its color plus the colour of any mana symbols in the card’s rules text. A card’s color identity is established before the game begins, and cannot be changed by game effects. The cards in a deck may not have any colours in their color identity which are not in the colour identity of the deck’s commander.
  3. A Commander deck must contain exactly X cards, including the commander. If you’re playing a companion, it must adhere to color identity and singleton rules. While it is not part of the deck, it is effectively a X+1st card.
    French Commander : X=100
    Leviathan Commander : X=100
    Archon Commander : X=100 minimum (you can play more than 100 in Archon)
    Historic Brawl : X=100
    Brawl : X=60
  4. 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.

Play Rules

  1. Players begin the game with X life.
    French Commander : X=20
    Leviathan Commander : X=30
    Archon Commander : X=20
    Brawl : X=25
  2. 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 two generic mana for each time it was previously cast from the command zone; this is an additional cost.
  3. 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.
  4. 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 commander-ness through any status changes, and is still a commander even when controlled by another player.
  5. If a player has been dealt 21 points of combat damage by a particular Commander during the game, that player loses a game. This rule doesn’t exist in Archon Commander and Brawl.
  6. Commanders are subject to the Legend rule; a player cannot control more than one legend with the same name.
  7. Parts of 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.