List of unreleased mechanics

There are some mechanics that have been designed by R&D but have been never released for several reasons as rules concerns. Some of them have been publicly explained over the years.

Unreleased colors

 * Purple For Planar Chaos.

Unreleased counters

 * Volatile counters By Mark Gottlieb, for Aether Revolt. When a card with a volatile counter dies, it deals 2 damage to target opponent.

Unreleased keyword actions

 * Double-tap  For Time Spiral. Cards that could tap, then tap again. Led to exert.
 * Hedronize For Battle for Zendikar. Roll a d8 and trigger a different effect depending on the value rolled.

Other unreleased mechanics

 * Advocate for Commander Legends. A triggered mechanic (like landfall or constellation) that triggers whenever your commander enters the battlefield or attacks.
 * Anchor For Time Spiral. ig creatures for cheap that required a mana payment for upkeep.
 * Bribe for Conspiracy: Take the Crown and Commander Legends. The spell gives you an effect. Then, each of your opponents may choose to draw a card. For each one that did, you get the effect again.
 * Call for Ixalan. A Dinosaur with call was usually a bigger Dinosaur, but one with a very cheap mana cost. You couldn't attack or block until you paid a one-time activation cost.
 * Camouflage (As long as this is untapped, it can't be the target of spells or abilities your opponents control) for Ikoria: Lair of Behemoths . This is similar to Paradise Druid.
 * Celestial (You may cast this card from Nyx. If it would enter the battlefield any other way, it goes to Nyx instead. If the card would leave the battlefield, it goes to Nyx instead. Your devotion to white reduces its cost by that much N) for Theros.
 * Clan for Kaldheim. A modified version of Leader, adapted for use as a tribal mechanic.  When you played a clan card, you chose a creature type, and the card affected that creature type. Then when you played a second clan card, you could rechoose your creature type, but both effects would affect the one chosen tribe.
 * Conjure [creature type] – [cost] for Strixhaven: School of Mages (If you cast this spell for [cost], when it enters the battlefield create an [appropriately sized, colored, and creature-typed] creature token.)
 * Cooperation (Whenever this creature deals combat damage to a player, put a +1/+1 counter on another target creature.) for Throne of Eldraine. A variant of the Slith mechanic.
 * "Creaturefall" for Selesnya in Guilds of Ravnica. Effects that trigger whenever a creature you control enters the battlefield.
 * "Deathfall" for Jund in Shards of Alara. Effects that trigger every time a creature dies.
 * Debt for Orzhov in Ravnica Allegiance. Spells give debt counters to opponents. At the beginning of their end step, they can get rid of any number of debt counters by paying  per debt counter. Then, as long as they have any debt counters remaining, they lose 1 life (not per debt counter just 1 life total regardless of how many debt counters they have).
 * Discipline N (Whenever this card becomes blocked, put N +1/+1 counters on this card.) for Throne of Eldraine.
 * Disguise for Dimir in Guilds of Ravnica. A ninjutsu variant where the creature with disguise is swapping with the attacking creature.
 * Endless for Future Sight. A keyword that made the creature return to your hand whenever it went to the graveyard from the battlefield.
 * Enhanced for Kaldheim. Enhanced meant that a creature was either enchanted or equipped. The ability went on creatures and gave them an extra ability if they were enhanced.
 * Enlist for Ixalan. Pay extra mana to create a creature token.
 * Familiar – [Effect] for Strixhaven: School of Mages (. . . if you control a creature token).
 * Finale For Rakdos in Ravnica Allegiance. Creature gains +N/+0 and some abilities, in exchange for being sacrificed at the end of turn.
 * Forbidden By Mark Rosewater, for Avacyn Restored. Card starts the game in exile.
 * Glorify For Amonkhet. If this creature dies when attacking, it grants a bonus to another creature.
 * Gunk By Richard Garfield.  Blank cards that didn't do anything but could be transferred to the opponent's deck.   It later appeared on a test card in the Mystery Booster set.
 * Hieroglyphics By Mark Rosewater, for Amonkhet. Pay to exile the card from the graveyard and draw a card.
 * Implements for Strixhaven: School of Mages. . Artifacts with two different tap abilities (one in each color of the school) and a third ability which was the combination of the two abilities.
 * Jewel For Guilds of Ravnica. It went on any instant or sorcery. After the card resolved, it got exiled. Then, whenever you cast another instant or sorcery, you could play the first card for free from exile. The idea behind it was that we built smaller effects that comboed together to do cool things.
 * Joust (When this creature is blocked, it gets +0/+N until end of turn. If not blocked, it gets +N/+0 instead.) for Throne of Eldraine.
 * "Land drop" for Zendikar. undefined: action (You may use land drop only if you haven’t played a land this turn. If you use land drop, you may not play a land for the remainder of the turn.)
 * Leader for "Salad", an unmade set intended to follow on from Dominaria. Whenever you played a leader card, you chose a leader from among your creatures, and that card granted an ability to your leader. If you played a second leader card, you had the option of changing who your leader was, but both cards would grant abilities to a single leader.
 * Mechanic I For Kaladesh. The Invention unreleased subtype (see below).
 * Mummify For Amonkhet. As embalm or eternalize, but makes the creature a 2/2 Zombie with wither.
 * Nostalgia By Mark Rosewater, for Time Spiral. It allowed you to put Vintage-legal cards into your deck that you might not normally be able to play.
 * Paincast For Rakdos in Return to Ravnica. Spells 1 mana cheaper for each point of damage you had dealt to an opponent this turn.
 * Plot For Amonkhet. A suspend variant representing you planning ahead.
 * Plunder For the Vampires and Pirates of Ixalan. Based on bloodthirst. When you cast these cards, if you had dealt combat damage to an opponent, the card received some kind of bonus.
 * Precedence For Azorius in Ravnica Allegiance. When this enters the battlefield, copy the ETB ability of any other creature you control.
 * Reckless For Gruul in Gatecrash. An ability that sacrificed the creature at the end of the turn when triggered.
 * Relentless For Time Spiral and inspired by Relentless Assault. Allowed creatures to attack twice each turn.
 * Resistance (This creature isn't a legal target of a spell or ability an opponent controls unless they pay as that spell or ability resolves) for Ikoria: Lair of Behemoths
 * Reverse Engineer For Kaladesh but pushed for Aether Revolt. It allowed you to copy an artifact and then that copy got sacrificed at end of turn, in the same way Heat Shimmer from Lorwyn does for creatures.
 * Roar By Mark Gottlieb, for the Dinosaurs of Ixalan. "You may pay [cost] and exile this card from your hand. If you do, you can still cast it this game. When CARDNAME roars .... [effect]". Led to Adventure.
 * Showoff  By Mark Rosewater, for Lorwyn. It allowed you to choose to reveal a card. If the card was revealed (from your hand or your library), then it could be played for its showoff cost, which was often cheaper than its normal mana cost.
 * "Sneaky" (This creature can't be blocked by creatures with power 3 or greater) for Ikoria: Lair of Behemoths.
 * Spellback for the Izzet League in Guilds of Ravnica. Somehow allowed players to "mix and match various instants and sorceries".
 * Stopwatch mechanic forces you to do certain actions in a set amount of time. Considered for Unstable.
 * Study – [cost] for Strixhaven: School of Mages. A mechanic where you can spend a resource (tapping at common, mana at uncommon) to add an ability to the card. Each card with study has two options of abilities to add. The second time you activate it, you can add the ability you didn't choose the first time.
 * Stygian for Theros Beyond Death.  When you play a card with the stygian mechanic, it brings onto the battlefield a special card from outside the game that represents the river of the dead. Creatures on the living side could only block creatures also on the living side while creatures on the dead side could only block creatures on the dead side.
 * Titan for Zendikar Rising. A kicker variant where the mana cost was always generic and always seven or more mana. It tended to mega-juice the spell. The flavor was that you were tapping into some residual Eldrazi energy that was seeped deep in the land.
 * Torment  Each opponent loses 3 life unless that player sacrifices a nonland permanent or discards a card. Reduced to an unkeyworded vertical cycle in Hour of Devastation.
 * Turmoil For Gruul, then Rakdos in Ravnica Allegiance. Effect that triggered at the end of your turn if an opponent had lost life during that turn.
 * Unique By Mark Rosewater, such mechanic is intended to narrow the Legendary rule effect which would be applied only to legendary permanents having the Unique ability.
 * Unnamed By Mark Rosewater, for Tempest. It allowed you to choose to start with the card in your opening hand. If you chose to do so, you had to begin with one card fewer.
 * Unnamed For Amonkhet. It made use of -1/-1 counters to represent the ruthlessness of Bolas.
 * Valiance (Whenever this creature deals combat damage to a player, put a +1/+1 counter on it.) for Throne of Eldraine. This is the Slith mechanic.
 * Ward (Once each turn, you may draw a card while this creature's the target of an opponent's spell or ability) for Ikoria: Lair of Behemoths

Unreleased lands

 * Barry's Land By Mark Rosewater, for Invasion. Later by Bill Rose, for Conflux. Printed as a test card in the Mystery Booster set.
 * Cave/City See Purple.

Unreleased subtypes

 * Quest (other mechanic than the released Quest enchantment ) For Zendikar and Throne of Eldraine.  Enchantments that gave you three tasks. You marked them with counters as you finished each one. Once all of them were completed, you could sacrifice the card for a big effect. Some got you the legendary artifacts for each court.
 * Invention for Kaladesh. Cards that let you fetch artifact cards from outside the game. The only unexplained mechanic of the five that the Kaladesh design team ended up making and liking. It got discarded for excess of mechanics.
 * Scroll for Strixhaven: School of Mages. The idea of scrolls was that they were artifact tokens that could hold an instant or sorcery in them. You then sacrificed them to cast the spell it was holding. Some cards let you make scrolls out of available instants or sorceries. Other cards made scrolls with spells (usually famous ones from Magic's past) already inside them.

Unreleased supertypes

 * Über-classes By Mark Rosewater, for Morningtide. Cards that affected "fighters" affected Soldiers and Warriors (and possibly Knights). "Mages" were Shaman and Wizards (and possibly Druids). "Scoundrel" meant Assassins and Rogues. Similar to the later batching.

Revealed mechanics
These formerly unreleased mechanics were eventually used in new sets.


 * Assemble Printed on a single card in Future Sight, but without any associated mechanical definition. Released in Unstable.
 * Last strike By Mark Rosewater, for Future Sight. Released in Unstable.
 * Link By Ken Nagle, for New Phyrexia. Supposedly the same [Redacted] mechanic that Aaron Forsythe hinted. Released in Eldritch Moon as meld.
 * Mechanic E By Mark Rosewater. Mechanic E, "energy", was originally designed for Mirrodin and finally printed in Kaladesh as energy counters.
 * Pwnage By Ken Nagle, for New Phyrexia. It allowed you to shuffle cards from your opponent's library into your own. It was killed by the rules, but released as Praetor's Grasp.
 * Q-mechanic By Mark Gottlieb, for Shadowmoor. It became the untap mechanic.
 * Skirmish for War of the Spark. "Create a Skirmish if one hasn't been created yet." The Skirmish token has a tiny "game board" on it showing a field of combat. When you perform one of the stated conditions, you advance on the field toward the opponent's side. If you have advanced enough, you win the skirmish. There is a payout for winning, a generated effect. Released in Dungeons & Dragons: Adventures in the Forgotten Realms as Venture into the dungeon.
 * Triple strike By Mark Rosewater, for Future Sight. Released in Unstable.