Mistwalker

Changeling (This card is every creature type.)
Flying
{1}{U}: Mistwalker gets +1/-1 until end of turn.

Mothdust Changeling

Changeling (This card is every creature type.)
Tap an untapped creature you control: Mothdust Changeling gains flying until end of turn.

Death-Mask Duplicant

Imprint — {1}: Exile target creature card from your graveyard.
As long as a card exiled with Death-Mask Duplicant has flying, Death-Mask Duplicant has flying. The same is true for fear, first strike, double strike, haste, landwalk, protection, and trample.

Renegade Doppelganger

Whenever another creature you control enters, you may have Renegade Doppelganger become a copy of that creature until end of turn. (If it does, it loses this ability for the rest of the turn.)

Wall of Stolen Identity

You may have Wall of Stolen Identity enter as a copy of any creature on the battlefield, except it's a Wall in addition to its other types and has defender. When you do, tap the copied creature and it doesn't untap during its controller's untap step for as long as you control Wall of Stolen Identity.

Stunt Double

Flash
You may have Stunt Double enter as a copy of any creature on the battlefield.

Wings of Velis Vel

Changeling (This card is every creature type.)
Until end of turn, target creature has base power and toughness 4/4, gains all creature types, and gains flying.

Orvar, the All-Form

Changeling
Whenever you cast an instant or sorcery spell, if it targets one or more other permanents you control, create a token that's a copy of one of those permanents.
When a spell or ability an opponent controls causes you to discard this card, create a token that's a copy of target permanent.

Nascent Metamorph

Whenever Nascent Metamorph attacks or blocks, target opponent reveals cards from the top of their library until they reveal a creature card. Nascent Metamorph becomes a copy of that card until end of turn. Then that player puts all cards revealed this way on the bottom of their library in a random order.

Mirror Image

You may have Mirror Image enter as a copy of a creature you control.

Primal Clay

As Primal Clay enters, it becomes your choice of a 3/3 artifact creature, a 2/2 artifact creature with flying, or a 1/6 Wall artifact creature with defender in addition to its other types. (A creature with defender can't attack.)

Undercover Operative

You may have Undercover Operative enter as a copy of any creature on the battlefield, except it enters with a shield counter on it if you control that creature. (If it would be dealt damage or destroyed, remove a shield counter from it instead.)

Identity Thief

Whenever Identity Thief attacks, you may exile another target nontoken creature. If you do, Identity Thief becomes a copy of that creature until end of turn. Return the exiled card to the battlefield under its owner's control at the beginning of the next end step.

Body Double

You may have Body Double enter as a copy of any creature card in a graveyard.

Sakashima's Will

Choose one. If you control a commander as you cast this spell, you may choose both instead.
• Target opponent chooses a creature they control. You gain control of it.
• Choose a creature you control. Each other creature you control becomes a copy of that creature until end of turn.

Cryptoplasm

At the beginning of your upkeep, you may have Cryptoplasm become a copy of another target creature, except it has this ability.

Sakashima of a Thousand Faces

You may have Sakashima of a Thousand Faces enter as a copy of another creature you control, except it has Sakashima of a Thousand Faces's other abilities.
The "legend rule" doesn't apply to permanents you control.
Partner (You can have two commanders if both have partner.)

Sakashima the Impostor

You may have Sakashima the Impostor enter as a copy of any creature on the battlefield, except its name is Sakashima the Impostor, it's legendary in addition to its other types, and it has "{2}{U}{U}: Return this creature to its owner's hand at the beginning of the next end step."

Mocking Doppelganger

Flash
You may have Mocking Doppelganger enter as a copy of a creature an opponent controls, except it has "Other creatures with the same name as this creature are goaded." (They attack each combat if able and attack a player other than you if able.)

Quicksilver Gargantuan

You may have Quicksilver Gargantuan enter as a copy of any creature on the battlefield, except it's 7/7.

Clone Shell

Imprint — When Clone Shell enters, look at the top four cards of your library, exile one face down, then put the rest on the bottom of your library in any order.
When Clone Shell dies, turn the exiled card face up. If it's a creature card, put it onto the battlefield under your control.

Mercurial Pretender

You may have Mercurial Pretender enter as a copy of a creature you control, except it has "{2}{U}{U}: Return this creature to its owner's hand."

Shadow Kin

Flash
At the beginning of your upkeep, each player mills three cards. You may exile a creature card from among the cards milled this way. If you do, Shadow Kin becomes a copy of that card, except it has this ability.

Vesuvan Shapeshifter

As Vesuvan Shapeshifter enters or is turned face up, you may choose another creature on the battlefield. If you do, until Vesuvan Shapeshifter is turned face down, it becomes a copy of that creature, except it has "At the beginning of your upkeep, you may turn this creature face down."
Morph {1}{U}

Ego Erasure

Changeling (This card is every creature type.)
Creatures target player controls get -2/-0 and lose all creature types until end of turn.

Primal Plasma

As Primal Plasma enters, it becomes your choice of a 3/3 creature, a 2/2 creature with flying, or a 1/6 creature with defender.

Clever Impersonator

You may have Clever Impersonator enter as a copy of any nonland permanent on the battlefield.

Metallic Mimic

As Metallic Mimic enters, choose a creature type.
Metallic Mimic is the chosen type in addition to its other types.
Each other creature you control of the chosen type enters with an additional +1/+1 counter on it.

Bloodline Pretender

Changeling (This card is every creature type.)
As Bloodline Pretender enters, choose a creature type.
Whenever another creature you control of the chosen type enters, put a +1/+1 counter on Bloodline Pretender.

Duplicant

Imprint — When Duplicant enters, you may exile target nontoken creature.
As long as a card exiled with Duplicant is a creature card, Duplicant has the power, toughness, and creature types of the last creature card exiled with Duplicant. It's still a Shapeshifter.

Universal Automaton

Changeling (This card is every creature type.)

Littjara Kinseekers

Changeling (This card is every creature type.)
When Littjara Kinseekers enters, if you control three or more creatures that share a creature type, put a +1/+1 counter on Littjara Kinseekers, then scry 1.

Clone

You may have Clone enter as a copy of any creature on the battlefield.

Glasspool Shore

Glasspool Shore enters tapped.
{T}: Add {U}.

Glasspool Mimic

You may have Glasspool Mimic enter as a copy of a creature you control, except it's a Shapeshifter Rogue in addition to its other types.

Glasspool Mimic // Glasspool Shore

Sakashima's Protege

Flash
Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
You may have Sakashima's Protege enter as a copy of any permanent that entered this turn.