Block Constructed

Block Constructed (also known as Block) was a format that allows for cards of a chosen block to be played, save any banned cards. As of April 2018, Wizards of the Coast no longer supports Block as the block system itself was discontinued in 2018.

Description
Constructed decks must contain a minimum of 60 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 15 cards.

With the exception of card named Plains, Island, Swamp, Mountain, and Forest, a player’s combined deck and sideboard may not contain more than four of any individual card, counted by its English card title equivalent. Snow-covered lands, despite being basic lands, are only permitted in formats that allow the Ice Age block to be used. This similarly applies to Wastes in Battle for Zendikar block.

According to Mark Rosewater, Block has proven over time to be an unpopular format almost exclusively played because Wizards of the Coast required it at Pro Tours and Pro Tour Qualifiers. He stated that it was being phased out because players almost never played it of their own volition. The format itself was dropped on the same day Dominaria, the first set of Three-and-One Model (in which blocks are no longer used), released.

Block formats
Blocks that were DCI sanctioned but never used in a Pro Tour and/or Grand Prix.
 * Ixalan block (Ixalan, Rivals of Ixalan)
 * Amonkhet block (Amonkhet, Hour of Devastation)
 * Kaladesh block (Kaladesh, Aether Revolt)
 * Shadows over Innistrad block (Shadows over Innistrad, Eldritch Moon)
 * Battle for Zendikar block (Battle for Zendikar, Oath of the Gatewatch)
 * Khans of Tarkir block (Khans of Tarkir, Fate Reforged, Dragons of Tarkir)

Blocks that had been used in at least one Pro Tour and/or Grand Prix.
 * Theros block (Theros, Born of the Gods, Journey into Nyx)
 * Return to Ravnica block (Return to Ravnica, Gatecrash, Dragon's Maze)
 * Innistrad block (Innistrad, Dark Ascension, Avacyn Restored)
 * Scars of Mirrodin block (Scars of Mirrodin, Mirrodin Besieged, New Phyrexia)
 * Zendikar block (Zendikar, Worldwake, Rise of the Eldrazi)
 * 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's 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, Homelands, Alliances)
 * Despite Homelands being replaced by Coldsnap in July 2006 for Ice Age block, Coldsnap itself was never actually used in Block's Pro Tour/Grand Prix events.

Innistrad block

 * Intangible Virtue
 * Lingering Souls

Mirrodin block

 * Æther Vial
 * Ancient Den
 * Arcbound Ravager
 * Darksteel Citadel
 * Disciple of the Vault
 * Great Furnace
 * Seat of the Synod</c>
 * Tree of Tales</c>
 * Vault of Whispers</c>
 * Skullclamp</c>

Masques block

 * Lin Sivvi, Defiant Hero</c>
 * Rishadan Port</c>

Urza's block

 * Gaea's Cradle</c>
 * Memory Jar</c> — The only card to have been the subject of an emergency ban in the format.
 * Serra's Sanctum</c>
 * Time Spiral</c>
 * Tolarian Academy</c>
 * Voltaic Key</c>
 * Windfall</c>

Tempest block

 * Cursed Scroll</c>

Mirage block

 * Squandered Resources</c>

Ice Age block

 * Amulet of Quoz</c>
 * <c>Thawing Glaciers</c>
 * <c>Timmerian Fiends</c> — Removed from banlist when Homelands was replaced by Coldsnap in the format.
 * <c>Zuran Orb</c>