Three Steps Ahead

Spree (Choose one or more additional costs.)
+ {1}{U} — Counter target spell.
+ {3} — Create a token that's a copy of target artifact or creature you control.
+ {2} — Draw two cards, then discard a card.

Nest of Scarabs

Whenever you put one or more -1/-1 counters on a creature, create that many 1/1 black Insect creature tokens.

Titania's Boon

Put a +1/+1 counter on each creature you control.

Slug

Overgrown Tomb

({T}: Add {B} or {G}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Hinterland Harbor

This land enters tapped unless you control a Forest or an Island.
{T}: Add {G} or {U}.

Hedge Maze

({T}: Add {G} or {U}.)
This land enters tapped.
When this land enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Yavimaya Coast

{T}: Add {C}.
{T}: Add {G} or {U}. This land deals 1 damage to you.

Snake

Toxrill, the Corrosive

At the beginning of each end step, put a slime counter on each creature you don't control.
Creatures you don't control get -1/-1 for each slime counter on them.
Whenever a creature you don't control with a slime counter on it dies, create a 1/1 black Slug creature token.
{U}{B}, Sacrifice a Slug: Draw a card.

Cephalid Facetaker

This creature can't be blocked.
At the beginning of combat on your turn, you may have this creature become a copy of another target creature until end of turn, except it's 1/4 and has "This creature can't be blocked."

Fire Nation Sentinels

Whenever a nontoken creature an opponent controls dies, put a +1/+1 counter on each creature you control.

Llanowar Wastes

{T}: Add {C}.
{T}: Add {B} or {G}. This land deals 1 damage to you.

Grim Affliction

Put a -1/-1 counter on target creature, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Three Visits

Search your library for a Forest card, put it onto the battlefield, then shuffle.

Espers to Magicite

Exile each opponent's graveyard. When you do, choose up to one target creature card exiled this way. Create a token that's a copy of that card, except it's an artifact and it loses all other card types.

Talisman of Resilience

{T}: Add {C}.
{T}: Add {B} or {G}. This artifact deals 1 damage to you.

Undergrowth Stadium

This land enters tapped unless you have two or more opponents.
{T}: Add {B} or {G}.

Cryptoplasm

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

Irenicus's Vile Duplication

Create a token that's a copy of target creature you control, except the token has flying and it isn't legendary.

Darkness Descends

Insect

Dimir Aqueduct

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

Nature's Lore

Search your library for a Forest card, put that card onto the battlefield, then shuffle.

Bayou

Lifecrafter's Gift

Put a +1/+1 counter on target creature, then put a +1/+1 counter on each creature you control with a +1/+1 counter on it.

Fated Infatuation

Create a token that's a copy of target creature you control. If it's your turn, scry 2.

Tropical Island

Beast Within

Destroy target permanent. Its controller creates a 3/3 green Beast creature token.

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.

Blight Rot

Put four -1/-1 counters on target creature.

Golgari Rot Farm

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

Growth Spiral

Draw a card. You may put a land card from your hand onto the battlefield.

Persistent Constrictor

At the beginning of each opponent's upkeep, they lose 1 life and you put a -1/-1 counter on up to one target creature they control.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Generous Patron

When this creature enters, support 2. (Put a +1/+1 counter on each of up to two other target creatures.)
Whenever you put one or more counters on a creature you don't control, draw a card.

Irma, Part-Time Mutant

At the beginning of combat on your turn, Irma becomes a copy of up to one other target creature you control, except her name is Irma, Part-Time Mutant and she has this ability. Then put a +1/+1 counter on her.

Mirror Image

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

Breeding Pool

({T}: Add {G} or {U}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Hapatra, Vizier of Poisons

Whenever Hapatra deals combat damage to a player, you may put a -1/-1 counter on target creature.
Whenever you put one or more -1/-1 counters on a creature, create a 1/1 green Snake creature token with deathtouch.

Clever Impersonator

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

Counterspell

Dusk Urchins

Whenever this creature attacks or blocks, put a -1/-1 counter on it.
When this creature dies, draw a card for each -1/-1 counter on it.

Beast

Silent Hallcreeper

This creature can't be blocked.
Whenever this creature deals combat damage to a player, choose one that hasn't been chosen —
• Put two +1/+1 counters on this creature.
• Draw a card.
• This creature becomes a copy of another target creature you control.

Deepfathom Echo

At the beginning of combat on your turn, this creature explores. Then you may have it become a copy of another creature you control until end of turn. (To have this creature explore, reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then put the card back or put it into your graveyard.)

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.

Sinister Gnarlbark

At the beginning of your end step, draw a card and blight 1. (Put a -1/-1 counter on a creature you control.)

Copy

(This token can be used to represent a token that's a copy of a permanent.)

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Necroskitter

Wither (This deals damage to creatures in the form of -1/-1 counters.)
Whenever a creature an opponent controls with a -1/-1 counter on it dies, you may return that card to the battlefield under your control.

Crumbling Ashes

At the beginning of your upkeep, destroy target creature with a -1/-1 counter on it.

Forest

Croaking Counterpart

Create a token that's a copy of target non-Frog creature, except it's a 1/1 green Frog.
Flashback {3}{G}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Double Major

Copy target creature spell you control, except it isn't legendary if the spell is legendary. (A copy of a creature spell becomes a token.)

Chameleon, Master of Disguise

You may have Chameleon enter as a copy of a creature you control, except his name is Chameleon, Master of Disguise.
Mayhem {2}{U} (You may cast this card from your graveyard for {2}{U} if you discarded it this turn. Timing rules still apply.)

Sol Ring

Toxic Deluge

As an additional cost to cast this spell, pay X life.
All creatures get -X/-X until end of turn.

Volrath, the Shapestealer

At the beginning of combat on your turn, put a -1/-1 counter on up to one target creature.
{1}: Until your next turn, Volrath becomes a copy of target creature with a counter on it, except it's 7/5 and it has this ability.

Assassin's Trophy

Destroy target permanent an opponent controls. Its controller may search their library for a basic land card, put it onto the battlefield, then shuffle.

Obelisk Spider

Reach
Whenever this creature deals combat damage to a creature, put a -1/-1 counter on that creature.
Whenever you put one or more -1/-1 counters on a creature, each opponent loses 1 life and you gain 1 life.

Putrefy

Destroy target artifact or creature. It can't be regenerated.

Moonshadow

Menace
This creature enters with six -1/-1 counters on it.
Whenever one or more permanent cards are put into your graveyard from anywhere while this creature has a -1/-1 counter on it, remove a -1/-1 counter from this creature.

Dread Tiller

When this creature enters, put a -1/-1 counter on target creature.
Whenever a creature with a -1/-1 counter on it dies, you may put a land card from your hand or graveyard onto the battlefield tapped.

Loyal Guardian

Trample
Lieutenant — At the beginning of combat on your turn, if you control your commander, put a +1/+1 counter on each creature you control.

Island

Drowned Catacomb

This land enters tapped unless you control an Island or a Swamp.
{T}: Add {U} or {B}.

Elf Warrior

Boseiju, Who Endures

{T}: Add {G}.
Channel — {1}{G}, Discard this card: Destroy target artifact, enchantment, or nonbasic land an opponent controls. That player may search their library for a land card with a basic land type, put it onto the battlefield, then shuffle. This ability costs {1} less to activate for each legendary creature you control.

High Perfect Morcant

Whenever High Perfect Morcant or another Elf you control enters, each opponent blights 1. (They each put a -1/-1 counter on a creature they control.)
Tap three untapped Elves you control: Proliferate. Activate only as a sorcery. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Watery Grave

({T}: Add {U} or {B}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Skinrender

When this creature enters, put three -1/-1 counters on target creature.

Underground River

{T}: Add {C}.
{T}: Add {U} or {B}. This land deals 1 damage to you.

Swamp

Deceptive Frostkite

Flying
You may have this creature enter as a copy of a creature you control with power 4 or greater, except it's a Dragon in addition to its other types and it has flying.

Urborg, Tomb of Yawgmoth

Each land is a Swamp in addition to its other land types.

Blowfly Infestation

Whenever a creature dies, if it had a -1/-1 counter on it, put a -1/-1 counter on target creature.

Skeleton Ship

When you control no Islands, sacrifice Skeleton Ship.
{T}: Put a -1/-1 counter on target creature.

Persist

Return target nonlegendary creature card from your graveyard to the battlefield with a -1/-1 counter on it.

Phantasmal Image

You may have this creature enter as a copy of any creature on the battlefield, except it's an Illusion in addition to its other types and it has "When this creature becomes the target of a spell or ability, sacrifice it."

Renegade Doppelganger

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

Negate

Dreamroot Cascade

This land enters tapped unless you control two or more other lands.
{T}: Add {G} or {U}.

Zagoth Triome

({T}: Add {B}, {G}, or {U}.)
This land enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Sunken Hollow

({T}: Add {U} or {B}.)
This land enters tapped unless you control two or more basic lands.

Spitting Dilophosaurus

Whenever this creature enters or attacks, put a -1/-1 counter on up to one target creature.
Creatures your opponents control with -1/-1 counters on them can't block.

Massacre Girl, Known Killer

Menace
Creatures you control have wither. (They deal damage to creatures in the form of -1/-1 counters.)
Whenever a creature an opponent controls dies, if its toughness was less than 1, draw a card.

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}.

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

Arcane Signet

Black Sun's Zenith

Put X -1/-1 counters on each creature. Shuffle Black Sun's Zenith into its owner's library.

Flourishing Defenses

Whenever a -1/-1 counter is put on a creature, you may create a 1/1 green Elf Warrior creature token.

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Talisman of Curiosity

{T}: Add {C}.
{T}: Add {G} or {U}. This artifact deals 1 damage to you.

Metamorphic Alteration

Enchant creature
As this Aura enters, choose a creature.
Enchanted creature is a copy of the chosen creature.