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.

Cheatyface

If Cheatyface is in your hand, you may sneak Cheatyface onto the battlefield. If an opponent catches you right away, that player may exile Cheatyface.
Flying

B.O.B. (Bevy of Beebles)

As B.O.B. enters, create four 1/1 blue Beeble creature tokens.
The number of loyalty counters on B.O.B. is equal to the number of Beebles you control. (Create or sacrifice Beebles whenever B.O.B. gains or loses loyalty.)
+1: Up to X target Beebles can't be blocked this turn, where X is the number of cards in your hand.
−1: Draw a card.

Johnny, Combo Player

{4}: Search your library for a card, put that card into your hand, then shuffle.

Mer Man

When this creature enters, you may draw a card.

Chicken à la King

Whenever a 6 is rolled on a six-sided die, put a +1/+1 counter on each Bird. (You may roll dice only when instructed to.)
Tap an untapped Bird you control: Roll a six-sided die. (Like now.)

Water Gun Balloon Game

As Water Gun Balloon Game enters, each player puts a pop! counter on "0."
Whenever a player casts a spell, move that player's pop! counter up one.
Whenever a player's pop! counter hits "5," that player creates a 5/5 pink Giant Teddy Bear creature token and resets all pop! counters to "0."

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.

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.

Carnivorous Death-Parrot

Flying
At the beginning of your upkeep, sacrifice Carnivorous Death-Parrot unless you say its flavor text.

Avatar of Me

This spell costs {1} more to cast for each ten years you've been alive.
Avatar of Me's power is equal to your height in feet and its toughness is equal to your American shoe size. Round to the nearest ½.
Avatar of Me is the color of your eyes.

Rock Lobster

Creatures named Scissors Lizard can't attack or block.

Island

Wall of Fortune

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

Underdome

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to pay Un-costs.

Magic Word

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

Alexander Clamilton

Whenever you cast a wordy spell, scry 2. (A spell is wordy if it has four or more lines of rules text.)
{1}{R}, {T}: Choose target creature you don't control. Reveal the top card of your library. Alexander Clamilton gets +X/+0 until end of turn, where X is the number of lines of rules text of the revealed card. Alexander Clamilton fights that creature.

Rings a Bell

As Rings a Bell enters, choose a word with four or more letters.
After you say the chosen word for the first time each turn, an opponent may ring or imitate a bell within five seconds. When no opponent does, draw a card.

Richard Garfield, Ph.D.

You may play cards as though they were other cards of your choice with the same mana cost. You can't choose the same card twice. (Mana cost includes color.)