Also called "french Duel Commander", Duel Commander is a 1 vs. 1 variant of the Commander format. As in Commander, you have a legendary creature (your commander) at the head of a 100-card deck based around it. All the cards in the deck must have the same "color identity" as the commander and you can only play one copy of each card (except basic lands). But unlike in Commander, you only have 20 starting life. In tournaments you can also "swap" your commander after game 1 and 2 of your match, but all matches start with your pre-selected commander.
In addition to the banned cards listed below there are some cards that cannot be used as the commander, which you can find in the official banlist.
These cards cannot be used in this format:
Ancestral Recall · Ancient Tomb · Back To Basics · Bazaar Of Baghdad · Black Lotus · Capture Of Jingzhou · Cavern Of Souls · Channel · Chrome Mox · Deflecting Swat · Dig Through Time · Eidolon Of The Great Revel · Emrakul, The Aeons Torn · Entomb · Fastbond · Field Of The Dead · Fierce Guardianship · Food Chain · Gaea's Cradle · Genesis Storm · Gifts Ungiven · Grim Monolith · Hermit Druid · High Tide · Humility · Imperial Seal · Jeweled Lotus · Karakas · Library Of Alexandria · Lion's Eye Diamond · Loyal Retainers · Lutri, The Spellchaser · Maddening Hex · Mana Crypt · Mana Drain · Mana Vault · Mishra's Workshop · Mox Diamond · Mox Emerald · Mox Jet · Mox Opal · Mox Pearl · Mox Ruby · Mox Sapphire · Mystical Tutor · Natural Order · Necrotic Ooze · Oath Of Druids · Polymorph · Price Of Progress · Protean Hulk · Ragavan, Nimble Pilferer · Scapeshift · Sensei's Divining Top · Serra's Sanctum · Sol Ring · Strip Mine · Temporal Manipulation · Thassa's Oracle · The Tabernacle At Pendrell Vale · Time Vault · Time Walk · Time Warp · Timetwister · Tinker · Tolarian Academy · Treasure Cruise · Uro, Titan Of Nature's Wrath · Vampiric Tutor · Wasteland · all ante/conspiracy cards
These cards are also legal in this format, despite not being part of the sets above:
"lifetime" Pass Holder · _____ _____ _____ Trespasser · _____ _____ Rocketship · _____ Balls Of Fire · _____ Bird Gets The Worm · _____ Goblin · _____-o-saurus · A Good Day To Pie · Aerialephant · Ambassador Blorpityblorpboop · Atomwheel Acrobats · Attempted Murder · Baaallerina · Balloon Stand · Bamboozling Beeble · Big Winner · Bioluminary · Black Hole · Blood Crypt · Blorbian Buddy · Boing! · Bounce Chamber · Breeding Pool · Bumper Cars · Captain Rex Nebula · Carnival Carnivore · Celebr-8000 · Centaur Of Attention · Chicken Troupe · Circuits Act · Clandestine Chameleon · Clown Car · Clown Extruder · Clowning Around · Comet, Stellar Pup · Coming Attraction · Command Performance · Complaints Clerk · Concession Stand · Costume Shop · Croakid Amphibonaut · Deadbeat Attendant · Dee Kay, Finder Of The Lost · Discourtesy Clerk · Dissatisfied Customer · Done For The Day · Down For Repairs · Draconian Gate-bot · Drop Tower · Eelectrocute · Embiggen · Exchange Of Words · Ferris Wheel · Fight The _____ Fight · Finishing Move · Foam Weapons Kiosk · Forest · Fortune Teller · Glitterflitter · Goblin Airbrusher · Godless Shrine · Grabby Tabby · Hall Of Mirrors · Hallowed Fountain · Haunted House · Information Booth · Island · Kiddie Coaster · Last Voyage Of The _____ · Line Cutter · Lineprancers · Magar Of The Magic Strings · Make A _____ Splash · Merry-go-round · Minotaur De Force · Monitor Monitor · Monoxa, Midway Manager · Motion Sickness · Mountain · Myra The Magnificent · Night Shift Of The Living Dead · Non-human Cannonball · One-clown Band · Overgrown Tomb · Pair O' Dice Lost · Park Bleater · Petting Zookeeper · Pick-a-beeble · Pin Collection · Plains · Priority Boarding · Prize Wall · Proficient Pyrodancer · Quick Fixer · Rad Rascal · Resolute Veggiesaur · Ride Guide · Robo-piñata · Roller Coaster · Roxi, Publicist To The Stars · Sacred Foundry · Sanguine Sipper · Saw In Half · Scampire · Scared Stiff · Seasoned Buttoneer · Six-sided Die · Slight Malfunction · Soul Swindler · Space Beleren · Spinnerette, Arachnobat · Spinny Ride · Squirrel Squatters · Starlight Spectacular · Steam Vents · Step Right Up · Stiltstrider · Stomping Ground · Storybook Ride · Strength-testing Hammer · Swamp · Swinging Ship · Sword-swallowing Seraph · Temple Garden · The Most Dangerous Gamer · The Space Family Goblinson · Ticket Turbotubes · Ticketomaton · Trash Bin · Tunnel Of Love · Tusk And Whiskers · Unlawful Entry · Vedalken Squirrel-whacker · Vegetation Abomination · Watery Grave · Wee Champion · Wicker Picker · Wizards Of The _____ · Wolf In _____ Clothing · Xenosquirrels