Commander, as officially titled by Wizards of the Coast, more commonly known as Elder Dragon Highlander (usually abbreviated to EDH) is a Highlander variant format with specific rules centered around a legendary creature called General or Commander. 
|“|| Created and popularized by fans, the Commander variant is usually played in casual Free-for-All multiplayer games, although two-player games are also popular. Each player starts at 40 life, and each player's deck is headed by a legendary creature designated as that deck's commander. A player's choice of commander determines which other cards can be played in the deck.
A recommended banned list for the Commander format is maintained by the rules committee at MTGCommander.net, not by Wizards of the Coast. On Magic Online, the Commander format follows that banned list. 
- Each player chooses a legendary creature which is called their General. Decks may use other legendary creatures as well.
- No cards in the deck of any player may have a Color identity that is not a subset of the color identity of his or her general. The color identity of a card is composed of every colored mana symbol that appears on that card—whether in the mana cost or the rules text. (Hybrid mana symbols count as both of their component symbols for this purpose, e.g. if a player uses Isamaru, Hound of Konda as a general, he or she can not use Kitchen Finks. Also, a player who uses Bosh, Iron Golem as a general may play Lightning Bolt.)
- Except for basic lands, player may not use more than one copy of any given card.
- Each deck must contain exactly 100 cards including the General.
- Normally, Sideboards are not allowed. Optionally, players may have a 10 card sideboard that they may use before the match after Generals are declared.
- Before play begins, each player's general is placed in the command zone.
- Players start at 40 life.
- So-called "Partial Paris" mulligans are used. Players may exile any amount of cards in their hands face down, then draw that many cards minus one from their deck. They may repeat the process as many times as they want, then shuffle all the exiled cards back into their deck.
- If a player would produce mana of colors that are not one of their General card's colors, they instead get that much colorless mana.
- Players may cast the General card from the command zone. However, the general costs more to cast for each time it has been cast this way. (If a General ends up in a player's hand, they may cast it as normal, and it neither costs more nor affects the cost to play it later.)
- If a General would be put into a graveyard from anywhere or exiled, its owner may put it in the command zone instead.
- If a player is dealt a total of 21 combat damage by any single General, he or she loses the game. The General does not have to be continuously in play. This is an additional state-based effect. Note that gaining life won't affect this total in any way.
Usually all Vintage legal cards are allowed for tournament play. While cards may be banned by specific playgroups or tournament organizers, banned lists usually feature the following cards:
Shahrazad is usually legal in Elder Dragon Highlander despite being banned in Vintage.
In addition, the following cards are usually banned from being used as a general (but not from being used in a deck):