Haberthrasher

Deathtouch
Whenever another creature you control that has a hat enters or a hat sticker is put on a creature you control, each opponent loses 1 life.

Sly Spy

Whenever this creature deals combat damage to a player, that player loses a finger until this creature leaves the battlefield. (The finger is chosen by its owner and can't roll dice or touch cards.)

Charm School

As this enchantment enters, choose a color and balance this enchantment on your head.
Prevent all damage that would be dealt to you by sources of the chosen color.
When this enchantment falls off your head, sacrifice this enchantment.

Exit Through the Grift Shop

Yell "Who wants a souvenir?" and announce the name of a nonland card in your graveyard. Each player in an Un-game who can hear you may bid life. You start the bidding at 0. The high bidder loses life equal to the high bid. They copy the card and may cast the copy without paying its mana cost. If you didn't win the bid, you gain life equal to the high bid and create that many Treasure tokens.

Rod of Spanking

{2}, {T}: This artifact deals 1 damage to target player. Then untap this artifact unless that player says "Thank you, sir. May I have another?"

Handcuffs

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

Zzzyxas's Abyss

At the beginning of your upkeep, destroy all nonland permanents with the first name alphabetically among nonland permanents.

Hangman

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

Plains

Side Quest

Target player in an Un-game you can see from your seat gains control of target creature you control until your next turn. At the beginning of your next upkeep, put two +1/+1 counters on that creature. (A creature is on the battlefield of only the game its controller is playing.)

Rat in the Hat

{T}, Sacrifice this creature: Until end of turn, you may cast target creature card that has a hat from your graveyard.

Kill! Destroy!

Destroy target nonblack creature.
Gotcha — If an opponent says "kill" or "destroy," you may say "Gotcha!" When you do, return Kill! Destroy! from your graveyard to your hand.

D00-DL, Caricaturist

When D00-DL, Caricaturist enters, create a 4/4 colorless Sketch creature token, which you have fifteen seconds to draw. The token has flying if it has wings in its art. The same is true for first strike and a sword, vigilance and a shield, menace and mean eyes, trample and horns, deathtouch and claws, lifelink and fangs, and haste and footwear.

Entirely Normal Armchair

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

T.A.P.P.E.R.

{T}, Tap an untapped creature you control that has a hat: Tap target creature.

Swamp

"Brims" Barone, Midway Mobster

When "Brims" Barone, Midway Mobster enters, put a +1/+1 counter on each other creature you control that has a hat.
"Brims" Barone, Midway Mobster has menace as long as you're wearing a hat.

Hat Trick

Target blocking or blocked creature you control gets +1/+1 and gains first strike until end of turn. If it has a hat, it gains double strike until end of turn. If you and that creature each have a hat, the creature gains triple strike until end of turn.

Farewell to Arms

As this enchantment enters, choose a hand attached to an opponent's arm.
When the chosen hand isn't behind its owner's back, sacrifice this enchantment. If you do, that player discards their hand . . . of cards. (The lawyers wouldn't let us do it the other way.)

Bog Humbugs

Flying
Whenever Bog Humbugs deals combat damage, hum that many notes of a festive song. If you can, put a +1/+1 counter on Bog Humbugs.