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."

Stop That

Target player discards a card.
Gotcha — If an opponent audibly flicks the cards in their hand, you may say "Gotcha!" When you do, return Stop That from your graveyard to your hand.

Growth Spurt

Roll a six-sided die. Target creature gets +X/+X until end of turn, where X is the result.

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.

Booster Tutor

Open a sealed Magic booster pack, reveal the cards, and put one of them into your hand. (Remove that card from your deck before beginning a new game.)

Bottle of Suleiman

{1}, Sacrifice Bottle of Suleiman: Flip a coin. If you win the flip, create a 5/5 colorless Djinn artifact creature token with flying. If you lose the flip, Bottle of Suleiman deals 5 damage to you.

Look at Me, I'm R&D

As Look at Me, I'm R&D comes into play, choose a number and a second number one higher or one lower than that number.
All instances of the first chosen number on permanents, spells, and cards in any zone are the second chosen number.

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.

Jack-in-the-Mox

{T}: Roll a six-sided die. This ability has the indicated effect.
1 — Sacrifice Jack-in-the-Mox and you lose 5 life.
2 — Add {W}.
3 — Add {U}.
4 — Add {B}.
5 — Add {R}.
6 — Add {G}.

Volrath's Motion Sensor

Enchant player
As Volrath's Motion Sensor enters, choose one of enchanted player's hands. That player balances Volrath's Motion Sensor on the back of that hand.
When Volrath's Motion Sensor falls off the chosen hand, sacrifice Volrath's Motion Sensor and enchanted player loses 3 life.

Mana Screw

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

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.)

Free-for-All

When Free-for-All enters, exile all creatures face down.
At the beginning of each player's upkeep, that player chooses a card exiled with Free-for-All at random and puts it onto the battlefield.
When Free-for-All leaves the battlefield, put all cards exiled with it into their owners' graveyards.

Timmy, Power Gamer

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

Johnny, Combo Player

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

Strategy, Schmategy

Roll a six-sided die. Strategy, Schmategy has the indicated effect.
1 — Do nothing.
2 — Destroy all artifacts.
3 — Destroy all lands.
4 — Strategy, Schmategy deals 3 damage to each creature and each player.
5 — Each player discards their hand and draws seven cards.
6 — Repeat this process two more times.

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.

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.

Goblin Bookie

{R}, {T}: Reflip any coin or reroll any die. (Activate only any time it makes sense.)

Chatter of the Squirrel

Create a 1/1 green Squirrel creature token.
Flashback {1}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Urza's Science Fair Project

{2}: Roll a six-sided die. Urza's Science Fair Project gets the indicated result.
1 — It gets -2/-2 until end of turn.
2 — Prevent all combat damage it would deal this turn.
3 — It gains vigilance until end of turn.
4 — It gains first strike until end of turn.
5 — It gains flying until end of turn.
6 — It gets +2/+2 until end of turn.

Side to Side

You and target opponent arm-wrestle. If you win, create a 3/3 green Ape creature token.

Infernal Spawn of Evil

Flying, first strike
{1}{B}, Reveal Infernal Spawn of Evil from your hand, Say "It's coming!": Infernal Spawn of Evil deals 1 damage to target opponent or planeswalker. Activate only during your upkeep and only once each turn.

Goblin Tutor

Roll a six-sided die. If you roll a 1, Goblin Tutor has no effect. Otherwise, search your library for the indicated card, reveal it, put it into your hand, then shuffle.
2 — A card named Goblin Tutor
3 — An enchantment
4 — An artifact
5 — A creature
6 — An instant or sorcery

Elvish Impersonators

As Elvish Impersonators enters, roll a six-sided die twice. Its base power becomes the first result and its base toughness becomes the second result.

Free-Range Chicken

{1}{G}: Roll two six-sided dice. If both results are the same, Free-Range Chicken gets +X/+X until end of turn, where X is that result. If the total of those results is equal to any other total you have rolled this turn for this ability, sacrifice it. (For example, if you roll two 3s, it gets +3/+3. If you roll a 4 and a 2 for this ability later that turn, sacrifice it.)

Emcee

Whenever another creature enters, you may stand up and say in a deep, booming voice, "Presenting . . . " and that creature's name. If you do, put a +1/+1 counter on that creature.

Game of Chaos

Flip a coin. If you win the flip, you gain 1 life and target opponent loses 1 life, and you decide whether to flip again. If you lose the flip, you lose 1 life and that opponent gains 1 life, and that player decides whether to flip again. Double the life stakes with each flip.

Look at Me, I'm the DCI

Ban a card other than a basic land card for the rest of the match. (All cards with that name in any zone or sideboard are removed from the match.)

Elvish House Party

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

Landfill

Choose a land type. Exile all lands you control of that type. Drop those cards, one at a time, onto the playing area from a height of at least one foot. Destroy each permanent completely covered by those cards. Then return the cards you dropped to the battlefield tapped.

Infernal Spawn of Infernal Spawn of Evil

Flying, first strike, trample
Once each turn, while you're searching your library, you may pay {1}{B}, reveal Infernal Spawn of Infernal Spawn of Evil from your library and say "I'm coming, too!" If you do, Infernal Spawn of Infernal Spawn of Evil deals 2 damage to a player of your choice.

Staying Power

"Until end of turn" and "this turn" effects don't end.

Flock of Rabid Sheep

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