Have

Double Header

Flying
When Double Header enters, you may return target permanent with a two-word name to its owner's hand.

Slaying Mantis

Just a second (As long as this spell is on the stack, players can't move permanents.)
Slaying Mantis enters by being thrown from a distance of at least three feet.
When Slaying Mantis enters, it fights each creature an opponent controls that it touched as it entered.

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{1}: This card's name becomes the card name of your choice. Activate anywhere, anytime.

Common Courtesy

Whenever a player casts a spell without asking your permission while casting it, counter that spell.
When a player asks you permission to cast a spell and you refuse, counter that spell and sacrifice Common Courtesy.

Earl of Squirrel

Squirrellink (Damage dealt by this creature also causes you to create that many 1/1 green Squirrel creature tokens.)
Creature tokens you control are Squirrels in addition to their other creature types.
Other Squirrels you control get +1/+1.

Letter Bomb

When Letter Bomb enters, sign it and shuffle it into target player's library. That player reveals each card they draw until they draw Letter Bomb. When that player draws Letter Bomb, it deals 19½ damage to them.

Animate Library

Enchant your library
Enchanted library is an artifact creature on the battlefield with power and toughness each equal to the number of cards in it. It's still a library.
If enchanted library would leave the battlefield, exile Animate Library instead.

Tug of War

Players play a subgame starting at 5 life and with up to three permanent cards with different names from their main-game library on the battlefield. As the subgame ends, the winner chooses one of the cards they put onto the battlefield as the subgame began and puts it onto the battlefield rather than shuffling it into their library.

Mystic Reflection

Choose target nonlegendary creature. The next time one or more creatures or planeswalkers enter this turn, they enter as copies of the chosen creature.
Foretell {U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Mirror Mirror

Mirror Mirror enters tapped.
{7}, {T}, Sacrifice Mirror Mirror: Choose target player. At the beginning of the next end step, exchange life totals with that player, exchange control of all permanents you and that player control, and exchange cards in your hands, cards in your libraries, and cards in your graveyards.

Entirely Normal Armchair

During your turn, if Entirely Normal Armchair is in your hand, you may hide it on the battlefield.
{0}: Return Entirely Normal Armchair to its owner's hand. Only your opponents may activate this ability and only if they see Entirely Normal Armchair.
{2}, Sacrifice Entirely Normal Armchair: Destroy target attacking creature.

Forest

Stone-Cold Basilisk

Whenever Stone-Cold Basilisk blocks or becomes blocked by a creature with fewer letters in its name, destroy that creature at end of combat. (Punctuation and spaces aren't letters.)
Whenever an opponent reads Stone-Cold Basilisk, that player is turned to stone until end of turn. Stoned players can't attack, block, cast spells, or activate abilities.

Keeper of the Sacred Word

As Keeper of the Sacred Word enters, choose a word.
Whenever an opponent says the chosen word, Keeper of the Sacred Word gets +3/+3 until end of turn.

Island

Now I Know My ABC's

At the beginning of your upkeep, if you control permanents with names that include all twenty-six letters of the English alphabet, you win the game.

Mobile Clone

Using a mobile device, take a picture of target creature. That device enters as a token that's a photocopy of the pictured creature. (Photocopies include Auras, Equipment, counters, and stickers in the shot. Don't touch other people's phones without permission and be careful if you do.)

Don't Have

Paper Tiger

Creatures named Rock Lobster can't attack or block.

Our Market Research Shows That Players Like Really Long Card Names So We Made this Card to Have the Absolute Longest Card Name Ever Elemental

Art rampage 2 (Whenever this creature becomes blocked by a creature, it gets +2/+2 for each creature in the blocker's art beyond the first.)

Killer Cosplay

Whenever Killer Cosplay becomes attached to a creature, choose a creature card name with an identical mana cost. That creature becomes a copy of the card with the chosen name until Killer Cosplay becomes unattached from it.
Equip {3}

Loose Lips

Enchant creature
As Loose Lips enters, choose a sentence with eight or fewer words.
Enchanted creature has flying.
Whenever enchanted creature deals damage to an opponent, that player may say the chosen sentence. If they don't, you draw two cards.

Scissors Lizard

Creatures named Paper Tiger can't attack or block.

Ashnod's Coupon

{T}, Sacrifice Ashnod's Coupon: Target player gets you target drink. You pay any costs for the drink.

Fat Ass

Fat Ass gets +2/+2 and has trample as long as you're eating. (Gum isn't food. We checked.)

Topsy Turvy

The phases of each player's turn are reversed. (The phases are, in reverse order, ending, second main, combat, first main, and beginning.)
As long as there are more than two players in the game, the turn order is reversed.

Mine, Mine, Mine!

When Mine, Mine, Mine! enters, each player puts their library into their hand.
Players have no maximum hand size and don't lose the game for drawing from an empty library.
Each player can't cast more than one spell each turn.
When Mine, Mine, Mine! leaves the battlefield, each player shuffles their hand and graveyard into their library.

Clay Pigeon

Flying
{1}, Throw Clay Pigeon into the air at least two feet above your head while seated: If you catch Clay Pigeon with one hand, prevent all damage a source of your choice would deal to you this turn and tap Clay Pigeon. Otherwise, sacrifice it.

Rock Lobster

Creatures named Scissors Lizard can't attack or block.

Animate Object

You get seven {TK}. Choose an inanimate object you own from outside the game. Put a power and toughness sticker on it. You may also put a name sticker, an art sticker, and/or an ability sticker on it. Put it onto the battlefield as a creature token.

Censorship

As Censorship enters, choose a word.
Whenever a player says the chosen word, Censorship deals 2 damage to that player.

Elvish House Party

Elvish House Party's power and toughness are each equal to the current hour, using the twelve-hour system.

It Came from Planet Glurg

You may have It Came from Planet Glurg enter as a copy of X different creatures on the battlefield. (It has their total power, total toughness, combined mana costs, all text boxes, names, art, and so on.)