Updated March 20, 2012

Constructed decks must contain a minimum of sixty cards. There is no maximum deck size; however, you must be able to shuffle your deck with no assistance. If a player wishes to use a sideboard, it must contain exactly fifteen cards.

With the exception of basic land cards, a player’s combined deck and sideboard may not contain more than four of any individual card, counted by its English card title equivalent. All cards named Plains, Island, Swamp, Mountain, and Forest are basic. (The five Ice Age block snow-covered lands -- Snow-Covered Plains, Snow-Covered Island, Snow-Covered Swamp, Snow-Covered Mountain, and Snow-Covered Forest -- are also basic lands. Note that snow-covered lands are permitted only in formats that allow expansions from the Ice Age block to be used.)

The DCI sanctions the following Block Constructed formats:

• Innistrad-Avacyn Restored block (Innistrad, Dark Ascension, Avacyn Restored [effective May 4, 2012])
• Scars of Mirrodin block (Scars of Mirrodin, Mirrodin Besieged, New Phyrexia)
• Zendikar-Rise of the Eldrazi block (Zendikar, Worldwake, Rise of the Eldrazi)
• Shards of Alara block (Shards of Alara, Conflux, Alara Reborn)
• Lorwyn-Shadowmoor block (Lorwyn, Morningtide, Shadowmoor, Eventide)
• Time Spiral block (Time Spiral, Planar Chaos, Future Sight)
• Ravnica block (Ravnica: City of Guilds, Guildpact, Dissension)
• Kamigawa block (Champions of Kamigawa, Betrayers of Kamigawa, Saviors of Kamigawa)
• Mirrodin block (Mirrodin, Darksteel, Fifth Dawn)
• Onslaught block (Onslaught, Legions, Scourge)
• Odyssey block (Odyssey, Torment, Judgment)
• Invasion block (Invasion, Planeshift, Apocalypse)
• Masques block (Mercadian Masques, Nemesis, Prophecy)
• Urza block (Urza's Saga, Urza's Legacy, Urza's Destiny)
• Tempest block (Tempest, Stronghold, Exodus)
• Mirage block (Mirage, Visions, Weatherlight)
• Ice Age block (Ice Age, Alliances, Coldsnap)

The following cards are banned in Block Constructed Tournaments:

• Intangible Virtue
  (Innistrad-Avacyn Restored block) (effective April 2, 2012)
• Lingering Souls
  (Innistrad-Avacyn Restored block) (effective April 2, 2012)
• AEther Vial
  (Mirrodin block)
• Ancient Den
  (Mirrodin block)
• Arcbound Ravager
  (Mirrodin block)
• Darksteel Citadel
  (Mirrodin block)
• Disciple of the Vault
  (Mirrodin block)
• Great Furnace
  (Mirrodin block)
• Seat of the Synod
  (Mirrodin block)
• Tree of Tales
  (Mirrodin block)
• Vault of Whispers
  (Mirrodin block)
• Skullclamp
  (Mirrodin block)
• Lin Sivvi, Defiant Hero
  (Masques block)
• Rishadan Port
  (Masques block)
• Gaea's Cradle
  (Urza block)
• Memory Jar
  (Urza block)
• Serra's Sanctum
  (Urza block)
• Time Spiral
  (Urza block)
• Tolarian Academy
  (Urza block)
• Voltaic Key
  (Urza block)
• Windfall
  (Urza block)
• Cursed Scroll
  (Tempest block)
• Squandered Resources
  (Mirage block)
• Amulet of Quoz
  (Ice Age Block)
• Thawing Glaciers
  (Ice Age block)
• Zuran Orb
  (Ice Age block)

Official information about Constructed formats and the Block Constructed format can be found in the Magic: The Gathering Tournament Rules.