Incoming!

Each player searches their library for any number of artifact, creature, enchantment, and/or land cards, puts them onto the battlefield, then shuffles.

Fraction Jackson

{G}, {T}: Return target card with a ½ on it from your graveyard to your hand.

B-I-N-G-O

Trample
Whenever a player casts a spell, put a chip counter on its mana value.
B-I-N-G-O gets +9/+9 for each set of three numbers in a row with chip counters on them.

S.N.O.T.

You may have S.N.O.T. enter stuck to another creature named S.N.O.T. If you do, all those creatures form a single creature.
S.N.O.T.'s power and toughness are each equal to the square of the number of cards named S.N.O.T. stuck together to form it. (One is a 1/1, two are a 4/4, three are a 9/9, and four are a 16/16. If you manage to get -1 S.N.O.T.s stuck together, it's a 1/1.)

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.

Name Dropping

Gotcha — If an opponent says a word that's in the name of a card in your graveyard, you may say "Gotcha!" When you do, return that card to your hand.

Fruitcake Elemental

Fruitcake Elemental is indestructible.
At the end of your turn, Fruitcake Elemental deals 7 damage to you.
{3}: Target player gains control of Fruitcake Elemental.

Timmy, Power Gamer

{4}: You may put a creature card from your hand onto the battlefield.

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.

Elvish House Party

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

Time Machine

{T}: Exile Time Machine and target nontoken creature you own. Return them to the battlefield at the beginning of your upkeep on your turn X in the next game you play with one of your opponents in this game, where X is the mana value of the exiled creature.

Land Aid '04

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle. If you sang a song the whole time you were searching and shuffling, you may untap that land.

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."

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.)

Forest

Flock of Rabid Sheep

Flip X coins. For each flip you win, create a 2/2 green Sheep creature token named Rabid Sheep.