Identity Thief

Whenever this creature attacks, you may exile another target nontoken creature. If you do, this creature 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.

Followed Footsteps

Enchant creature
At the beginning of your upkeep, create a token that's a copy of enchanted creature.

Clever Impersonator

You may have this creature enter as a copy of any nonland permanent on the battlefield.

Cryptoplasm

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

Predator Ooze

Indestructible (Damage and effects that say "destroy" don't destroy this creature.)
Whenever this creature attacks, put a +1/+1 counter on it.
Whenever a creature dealt damage by this creature this turn dies, put a +1/+1 counter on this creature.

Mirror Mockery

Enchant creature
Whenever enchanted creature attacks, you may create a token that's a copy of that creature. Exile that token at end of combat.

Island

Reef Worm

When this creature dies, create a 3/3 blue Fish creature token with "When this token dies, create a 6/6 blue Whale creature token with 'When this token dies, create a 9/9 blue Kraken creature token.'"

Temple of Mystery

This land enters tapped.
When this land enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)
{T}: Add {G} or {U}.

Mercurial Pretender

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

Biovisionary

At the beginning of the end step, if you control four or more creatures named Biovisionary, you win the game.

Altered Ego

This spell can't be countered.
You may have this creature enter as a copy of any creature on the battlefield, except it enters with X additional +1/+1 counters on it.

Vizier of Many Faces

You may have this creature enter as a copy of any creature on the battlefield, except if this creature was embalmed, the token has no mana cost, it's white, and it's a Zombie in addition to its other types.
Embalm {3}{U}{U}

Thornwood Falls

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {G} or {U}.

Emerald Medallion

Green spells you cast cost {1} less to cast.

Forced Adaptation

Enchant creature
At the beginning of your upkeep, put a +1/+1 counter on enchanted creature.

Simic Growth Chamber

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {G}{U}.

Master Biomancer

Each other creature you control enters with a number of additional +1/+1 counters on it equal to this creature's power and as a Mutant in addition to its other types.

Progenitor Mimic

You may have this creature enter as a copy of any creature on the battlefield, except it has "At the beginning of your upkeep, if this creature isn't a token, create a token that's a copy of this creature."

Fog Bank

Defender (This creature can't attack.)
Flying
Prevent all combat damage that would be dealt to and dealt by this creature.

Gigantoplasm

You may have this creature enter as a copy of any creature on the battlefield, except it has "{X}: This creature has base power and toughness X/X."

Body Double

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

Relm's Sketching

Create a token that's a copy of target artifact, creature, or land.

Wall of Air

Defender, flying (This creature can't attack, and it can block creatures with flying.)