Unfinity

Katerina of Myra's Marvels

Legendary Creature — Human Performer

As Katerina of Myra's Marvels enters, choose a letter.
Whenever you cast a spell whose name begins with the chosen letter, create a white 2/2 Cat creature token with flying.
Partner (You can have two commanders if they both have partner.)

Legendary Creature — Merfolk Performer

As Fluros of Myra's Marvels enters, choose a number greater than 0.
Whenever you cast a spell with power, toughness, or loyalty equal to the chosen number, target artifact or creature becomes an artifact creature with base power and toughness X/X until end of turn, where X is the chosen number.
Partner

Fluros of Myra's Marvels

Legendary Creature — Vampire Performer

As Nocturno of Myra's Marvels enters, choose a word with five or more letters.
Whenever you cast a spell with the chosen word in its rules text, you draw a card and you lose 2 life.
Partner (You can have two commanders if both have partner.)

Nocturno of Myra's Marvels

Legendary Creature — Devil Performer

Haste
When Devil K. Nevil enters, jump it over any number of creatures. If it clears those creatures, put that many +1/+1 counters on it. (You can see a jumping demonstration at DevilKNevil.com.)

Devil K. Nevil

Treasure

Ignacio of Myra's Marvels

Legendary Creature — Lizard Performer

As Ignacio of Myra's Marvels enters, choose armor, blood, book, bottle, fang, fire, scroll, spear, sword, or water.
Whenever you cast a spell with the chosen object in its art, create two Treasure tokens.
Partner (You can have two commanders if both have partner.)

Legendary Creature — Elf Performer

As Hardy of Myra's Marvels enters, choose a number.
Whenever you cast a spell with the chosen number of lines of flavor text, put that many +1/+1 counters on target creature.
Partner (You can have two commanders if both have partner.)

Hardy of Myra's Marvels

Ambassador Blorpityblorpboop

Ticket Bucket-Bot

Legendary Creature — Alien Advisor Guest

When Ambassador Blorpityblorpboop enters, you get {TK}{TK}{TK}, then you may put a sticker on a nonland permanent you own.
At the beginning of each combat, you may have Ambassador Blorpityblorpboop's base power become equal to the total power of all stickers on permanents you control and its base toughness become equal to those stickers' total toughness.

Legendary Creature — Minotaur Performer

{1}{B}{R}: Note the name of target instant or sorcery card in your graveyard and put it onto the battlefield face down. It's a 3/3 creature with "Whenever this creature deals combat damage to a player, you may create a copy of the card with the noted name. You may cast the copy without paying its mana cost" and "If this creature would leave the battlefield, exile it instead of putting it anywhere else."

Magar of the Magic Strings

Legendary Creature — Goblin Guest

The Space Family Goblinson has trample as long as you've rolled three or more dice this turn.
Whenever you roll a die, put a +1/+1 counter on The Space Family Goblinson.

The Space Family Goblinson

Legendary Creature — Spider Performer

Reach
When Spinnerette enters, open an Attraction.
As long as you control three or more Attractions, Spinnerette gets +2/+0 and has menace.

Spinnerette, Arachnobat

Tusk and Whiskers

Legendary Creature — Elephant Mouse Performer

Whenever you put an ability sticker on a creature, put a +1/+1 counter on that creature.
{2}{G}{W}, {T}: You get {TK}. You may put a sticker on a nonland permanent you own.

Squirrel

Comet, Stellar Pup

Legendary Planeswalker — Comet

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 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's loyalty ability two more times this turn.