Slip Out the Back

Put a +1/+1 counter on target creature. It phases out. (Treat it and anything attached to it as though they don't exist until its controller's next turn.)

Experiment Kraj

Experiment Kraj has all activated abilities of each other creature with a +1/+1 counter on it.
{T}: Put a +1/+1 counter on target creature.

Llanowar Wastes

{T}: Add {C}.
{T}: Add {B} or {G}. Llanowar Wastes deals 1 damage to you.

Soul Diviner

{T}, Remove a counter from an artifact, creature, land, or planeswalker you control: Draw a card.

Herald of Secret Streams

Creatures you control with +1/+1 counters on them can't be blocked.

Farseek

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

Obelisk Spider

Reach
Whenever Obelisk Spider 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.

Nest of Scarabs

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

Midnight Banshee

Wither (This deals damage to creatures in the form of -1/-1 counters.)
At the beginning of your upkeep, put a -1/-1 counter on each nonblack creature.

Polymorphist's Jest

Until end of turn, each creature target player controls loses all abilities and becomes a blue Frog with base power and toughness 1/1.

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.)

Soul Snuffers

When Soul Snuffers enters, put a -1/-1 counter on each creature.

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.)

Arcane Lighthouse

{T}: Add {C}.
{1}, {T}: Until end of turn, creatures your opponents control lose hexproof and shroud and can't have hexproof or shroud.

Aqueous Form

Enchant creature
Enchanted creature can't be blocked.
Whenever enchanted creature attacks, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Snakeskin Veil

Put a +1/+1 counter on target creature you control. It gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Talisman of Dominance

{T}: Add {C}.
{T}: Add {U} or {B}. Talisman of Dominance deals 1 damage to you.

Biophagus

Genomic Enhancement — {T}: Add one mana of any color. If this mana is spent to cast a creature spell, that creature enters with an additional +1/+1 counter on it.

Fathom Mage

Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)
Whenever a +1/+1 counter is put on Fathom Mage, you may draw a card.

Quillspike

{B/G}, Remove a -1/-1 counter from a creature you control: Quillspike gets +3/+3 until end of turn.

Wickerbough Elder

Wickerbough Elder enters with a -1/-1 counter on it.
{G}, Remove a -1/-1 counter from Wickerbough Elder: Destroy target artifact or enchantment.

Astral Cornucopia

Astral Cornucopia enters with X charge counters on it.
{T}: Choose a color. Add one mana of that color for each charge counter on Astral Cornucopia.

Inspiring Call

Draw a card for each creature you control with a +1/+1 counter on it. Those creatures gain indestructible until end of turn. (Damage and effects that say "destroy" don't destroy them.)

Agent's Toolkit

Agent's Toolkit enters with a +1/+1 counter, a flying counter, a deathtouch counter, and a shield counter on it. (If it would be dealt damage or destroyed, remove a shield counter from it instead.)
Whenever a creature you control enters, you may move a counter from Agent's Toolkit onto that creature.
{2}, Sacrifice Agent's Toolkit: Draw a card.

Arcane Signet

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

Cold-Eyed Selkie

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Whenever Cold-Eyed Selkie deals combat damage to a player, you may draw that many cards.

Hapatra, Vizier of Poisons

Whenever Hapatra, Vizier of Poisons 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.

Fellwar Stone

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

Karn's Bastion

{T}: Add {C}.
{4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Thrummingbird

Flying
Whenever Thrummingbird deals combat damage to a player, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Sudden Spoiling

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Until end of turn, creatures target player controls lose all abilities and have base power and toughness 0/2.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

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.

Devoted Druid

{T}: Add {G}.
Put a -1/-1 counter on Devoted Druid: Untap Devoted Druid.

Sunken Hollow

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

Forest

Negate

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.

Generous Patron

When Generous Patron 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.

Sol Ring

Infernal Grasp

Destroy target creature. You lose 2 life.

Flourishing Defenses

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

Master Biomancer

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

Tainted Strike

Target creature gets +1/+0 and gains infect until end of turn. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Phyrexian Reclamation

{1}{B}, Pay 2 life: Return target creature card from your graveyard to your hand.

Talisman of Resilience

{T}: Add {C}.
{T}: Add {B} or {G}. Talisman of Resilience deals 1 damage to you.

Overgrown Tomb

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

Unspeakable Symbol

Pay 3 life: Put a +1/+1 counter on target creature.

Swamp

Cephalid Constable

Whenever Cephalid Constable deals combat damage to a player, return up to that many target permanents that player controls to their owner's hand.

Heroic Intervention

Permanents you control gain hexproof and indestructible until end of turn.

Sword of Truth and Justice

Equipped creature gets +2/+2 and has protection from white and from blue.
Whenever equipped creature deals combat damage to a player, put a +1/+1 counter on a creature you control, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Equip {2}

Invisible Stalker

Hexproof (This creature can't be the target of spells or abilities your opponents control.)
Invisible Stalker can't be blocked.

Crumbling Ashes

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

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

Inexorable Tide

Whenever you cast a spell, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Blowfly Infestation

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

Cultivate

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Three Visits

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

An Offer You Can't Refuse

Counter target noncreature spell. Its controller creates two Treasure tokens. (They're artifacts with "{T}, Sacrifice this token: Add one mana of any color.")

Nesting Grounds

{T}: Add {C}.
{1}, {T}: Move a counter from target permanent you control onto another target permanent. Activate only as a sorcery.

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

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, the Shapestealer becomes a copy of target creature with a counter on it, except it's 7/5 and it has this ability.

Champion of Lambholt

Creatures with power less than Champion of Lambholt's power can't block creatures you control.
Whenever another creature you control enters, put a +1/+1 counter on Champion of Lambholt.

Deathcap Glade

Deathcap Glade enters tapped unless you control two or more other lands.
{T}: Add {B} or {G}.

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Command Tower

Spark Double

You may have Spark Double enter as a copy of a creature or planeswalker you control, except it enters with an additional +1/+1 counter on it if it's a creature, it enters with an additional loyalty counter on it if it's a planeswalker, and it isn't legendary.

Tezzeret's Gambit

({U/P} can be paid with either {U} or 2 life.)
Draw two cards, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Nature's Lore

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

Persist

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

Black Sun's Zenith

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

Island

Kodama of the West Tree

Reach
Modified creatures you control have trample. (Equipment, Auras you control, and counters are modifications.)
Whenever a modified creature you control deals combat damage to a player, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Arcane Denial

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep.
You draw a card at the beginning of the next turn's upkeep.

Incubation Druid

{T}: Add one mana of any type that a land you control could produce. If Incubation Druid has a +1/+1 counter on it, add three mana of that type instead.
{3}{G}{G}: Adapt 3. (If this creature has no +1/+1 counters on it, put three +1/+1 counters on it.)

Evolution Sage

Landfall — Whenever a land you control enters, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Forgotten Ancient

Whenever a player casts a spell, you may put a +1/+1 counter on Forgotten Ancient.
At the beginning of your upkeep, you may move any number of +1/+1 counters from Forgotten Ancient onto other creatures.