Eldrazi Guacamole Tightrope

{TK}{TK} — Haste
{TK}{TK}{TK}{TK}{TK} — You may cast this card from your graveyard by paying 2 life in addition to paying its other costs.
{TK}{TK} — 1/4
{TK}{TK}{TK} — 5/3

Yawgmoth Merfolk Soul

{TK}{TK} — When this permanent leaves the battlefield, target player discards a card.
{TK}{TK}{TK}{TK}{TK} — When this permanent leaves the battlefield, create five 1/1 white Clown Robot artifact creature tokens.
{TK}{TK} — 3/3
{TK}{TK}{TK}{TK} — 6/5

Myra the Magnificent

Whenever you cast an instant or sorcery spell from your hand, open an Attraction.
{X}, {T}: Exile target instant or sorcery card with mana value X from your graveyard and choose an Attraction you control that doesn't have a midway counter on it. Put a midway counter on it. For as long as that Attraction is on the battlefield, whenever you visit it, copy the exiled card. You may cast the copy without paying its mana cost.

Opening Ceremony

Add {W}{U}{B}{R}{G}{C}. You may open a sealed Magic booster pack. Until end of turn, you may cast spells from among the cards in that booster pack.

Killer Cosplay

Whenever Killer Cosplay becomes attached to a creature, choose a creature card name with an identical mana cost. That creature becomes a copy of the card with the chosen name until Killer Cosplay becomes unattached from it.
Equip {3}

Comet, Stellar Pup

0: Roll a six-sided die.
1 or 2 — [+2], then create two 1/1 green Squirrel creature tokens. They gain haste until end of turn.
3 — [−1], then return a card with mana value 2 or less from your graveyard to your hand.
4 or 5 — Comet, Stellar Pup deals damage equal to the number of loyalty counters on him to a creature or player, then [−2].
6 — [+1], and you may activate Comet, Stellar Pup's loyalty ability two more times this turn.

Jermane, Pride of the Circus

{G}, {T}: Put two +1/+1 counters on target creature with four or more legs.
{1}{G}{G}, {T}: Until end of turn, all creatures able to block target creature with four or more legs do so.

Pie-roclasm

Pie-roclasm deals π damage to each non-Clown creature. (How to calculate π isn't important. It's a smidgen more than 3.)

Omniclown Colossus

Affinity for Clowns (This spell costs {1} less to cast for each Clown you control.)
Trample

Omniclown Colossus // Pie-roclasm

Haunted House

Visit — Return target creature card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of your next end step.

Goblin Coward Parade

{TK}{TK} — Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
{TK}{TK}{TK} — When this permanent leaves the battlefield, you may destroy target creature with power 4 or greater.
{TK}{TK} — 2/3
{TK}{TK}{TK}{TK} — 8/4

Carnival Elephant Meteor

{TK}{TK} — Sacrifice this permanent: Draw two cards.
{TK}{TK}{TK} — Whenever this creature attacks, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
{TK}{TK} — 4/1
{TK}{TK}{TK}{TK}{TK} — 8/7

Grand Marshal Macie

You may choose not to untap Grand Marshal Macie during your untap step. If you do, put a pause counter on it, then you lose 1 life for each pause counter on it.
Whenever Macie becomes untapped, remove all pause counters from it.
{2}, {T}: Choose an "until end of turn" or "this turn" effect. As long as Macie remains tapped, that effect doesn't end.

Unique Charmed Pants

{TK}{TK} — {T}: Add one mana of any color.
{TK}{TK}{TK} — Whenever this creature attacks, if it's not a Brushwagg, it gets +X/+0 until end of turn, where X is the number of supertypes, card types, and subtypes it has.
{TK}{TK} — 5/1
{TK}{TK}{TK}{TK} — 4/8

Blue Ribbon

When Blue Ribbon enters, ask a person outside the game which creature you control is most deserving of a blue ribbon. Attach Blue Ribbon to that creature.
Equipped creature has best in show. (Whenever another creature becomes the target of a spell or ability you control, you may copy that spell or ability. If you do, the copy targets this creature.)
Equip {3}