Destroy target creature with reminder text. (Reminder text is any italicized text in parentheses that explains rules you already know.)

Snickering Squirrel

You may tap Snickering Squirrel to increase the result of a die any player rolled by 1.

Flaccify

Counter target spell unless its controller pays {3}{½}.

Mad Science Fair Project

{T}: Roll a six-sided die. On a 3 or lower, target player adds {C}. Otherwise, that player adds one mana of any color they choose.

Jumbo Imp

Flying
As Jumbo Imp enters, roll a six-sided die. Jumbo Imp enters with a number of +1/+1 counters on it equal to the result.
At the beginning of your upkeep, roll a six-sided die and put a number of +1/+1 counters on Jumbo Imp equal to the result.
At the beginning of your end step, roll a six-sided die and remove a number of +1/+1 counters from Jumbo Imp equal to the result.

Border Guardian

Whenever you cast a silver-bordered spell, put a +1/+1 counter on Border Guardian.
Whenever you cast a black-bordered spell, Border Guardian can't be blocked this turn.
Whenever you cast a white-bordered spell, Border Guardian gains double strike until end of turn.

Poultrygeist

Flying
Whenever a creature dies, you may roll a six-sided die. If you roll a 1, sacrifice Poultrygeist. Otherwise, put a +1/+1 counter on Poultrygeist.

Summon the Pack

Open a sealed Magic booster pack, reveal the cards, and put all creature cards revealed this way onto the battlefield under your control. They're Zombies in addition to their other types. (Remove those cards from your deck before beginning a new game.)

Handcuffs

As Handcuffs enters, choose a player.
When the chosen player's hands aren't touching each other, sacrifice Handcuffs and that player sacrifices three permanents.

Magical Hacker

{U}: Change the text of target spell or permanent by replacing all instances of + with -, and vice versa, until end of turn.

Time Out

Roll a six-sided die. Put target nonland permanent into its owner's library just beneath the top X cards of that library, where X is the result.

Krark's Other Thumb

If you would roll a die, instead roll two of those dice and ignore one of those results.

Wall of Fortune

Defender
You may tap an untapped Wall you control to have any player reroll a die that player rolled.

Fowl Play

Enchant creature
Enchanted creature loses all abilities and is a Bird creature with base power and toughness 1/1.

Tainted Monkey

{T}: Choose a word. Target player mills a card. If a card with the chosen word in its text box was milled this way, they lose 3 life.

_____

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

Steel Squirrel

Whenever you roll a 5 or higher on a die, Steel Squirrel gets +X/+X until end of turn, where X is the result.
{6}: Roll a six-sided die.

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.

Sly Spy

Whenever Sly Spy deals combat damage to a player, that player reveals their hand. You choose a card from it with the longest name. That player discards that card.

Watermarket

{T}: Add {C}{C}. Spend this mana only to cast spells with watermarks.

Mana Screw

{1}: Flip a coin. If you win the flip, add {C}{C}. Activate only as an instant.

My First Tome

{1}, {T}: Say the flavor text on a card in your hand. Target opponent guesses that card's name. You may reveal that card. If you do and they guessed wrong, you draw a card.

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.

Hangman

As Hangman enters, secretly note a word with six to eight letters.
{1}: Target player who doesn't control Hangman guesses the noted word or an unguessed letter in that word. If they guess wrong, put a +1/+1 counter on Hangman. Any player may activate this ability.
When a player guesses the noted word or all of its letters, sacrifice Hangman.

More or Less

Add or subtract 1 or one from a number or number word on target spell or permanent until end of turn.

Spell Counter

Counter target spell.
Gotcha — If an opponent says "spell" or "counter," you may say "Gotcha!" When you do, return Spell Counter from your graveyard to your hand.

Numbing Jellyfish

When this creature enters, roll a six-sided die. Target player mills X cards, where X is the result.

Big Boa Constrictor

When this creature enters, roll a six-sided die. Target opponent loses life equal to the result.

Blurry Beeble

Blurry (This creature can be blocked only if defending player was wearing glasses as it was cast.)
Whenever Blurry Beeble deals combat damage to a player, you may draw a card. If you do, discard a card.

Number Crunch

Return target permanent to its owner's hand.
Gotcha — If an opponent says a number, you may say "Gotcha!" When you do, return Number Crunch from your graveyard to your hand.

Magic Word

Enchant creature
As Magic Word enters, choose a word.
Whisper the chosen word: Tap enchanted creature.

Inhumaniac

At the beginning of your upkeep, roll a six-sided die. On a 3 or 4, put a +1/+1 counter on Inhumaniac. On a 5 or higher, put two +1/+1 counters on it. On a 1, remove all +1/+1 counters from Inhumaniac.