Vivisurgeon's Insight

Draw three cards. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Dreamtide Whale

Vanishing 2 (This creature enters with two time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
Whenever a player casts their second spell each turn, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Swamp

Maha, Its Feathers Night

Flying, trample
Ward—Discard a card.
Creatures your opponents control have base toughness 1.

Catacomb Slug

Reject Imperfection

Counter target spell. If that spell's mana value was 3 or less, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Blightbelly Rat

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
When this creature dies, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Kindred Dominance

Choose a creature type. Destroy all creatures that aren't of the chosen type.

Giant Slug

{5}: At the beginning of your next upkeep, choose a basic land type. This creature gains landwalk of the chosen type until the end of that turn. (It can't be blocked as long as defending player controls a land of that type.)

Fuel for the Cause

Counter target spell, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Counterspell

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.)

Contagion Clasp

When this artifact enters, put a -1/-1 counter on target creature.
{4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Staff of Compleation

{T}, Pay 1 life: Destroy target permanent you own.
{T}, Pay 2 life: Add one mana of any color.
{T}, Pay 3 life: Proliferate.
{T}, Pay 4 life: Draw a card.
{5}: Untap this artifact.

Sol Ring

Bottomless Vault

This land enters tapped.
You may choose not to untap this land during your untap step.
At the beginning of your upkeep, if this land is tapped, put a storage counter on it.
{T}, Remove any number of storage counters from this land: Add {B} for each storage counter removed this way.

Arcane Signet

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

The Meathook Massacre

When The Meathook Massacre enters, each creature gets -X/-X until end of turn.
Whenever a creature you control dies, each opponent loses 1 life.
Whenever a creature an opponent controls dies, you gain 1 life.

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.)

Necrosynthesis

Enchant creature
Enchanted creature has "Whenever another creature dies, put a +1/+1 counter on this creature."
When enchanted creature dies, look at the top X cards of your library, where X is its power. Put one of those cards into your hand and the rest on the bottom of your library in a random order.

Skullcap Snail

When this creature enters, target opponent exiles a card from their hand.

Incremental Blight

Put a -1/-1 counter on target creature, two -1/-1 counters on another target creature, and three -1/-1 counters on a third target creature.

Thrummingbird

Flying
Whenever this creature 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.)

Throne of Geth

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

Dimir Signet

Drivnod, Carnage Dominus

If a creature dying causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
{B/P}{B/P}, Exile three creature cards from your graveyard: Put an indestructible counter on Drivnod. ({B/P} can be paid with either {B} or 2 life.)

Gluttonous Slug

Menace
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.)

Flatline

Creatures your opponents control have base power and toughness 0/1 until end of turn.

Mass Diminish

Until your next turn, creatures target player controls have base power and toughness 1/1.
Flashback {3}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Salt Marsh

This land enters tapped.
{T}: Add {U} or {B}.

Drown in Ichor

Target creature gets -4/-4 until end of turn. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Dimir Aqueduct

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

Terramorphic Expanse

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Talisman of Dominance

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

Steady Progress

Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Draw a card.

Mirkwood Bats

Flying
Whenever you create or sacrifice a token, each opponent loses 1 life.

Slaughter Specialist

When this creature enters, each opponent creates a 1/1 white Human creature token.
Whenever a creature an opponent controls dies, put a +1/+1 counter on this creature.

Temple of Deceit

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 {U} or {B}.

Blood Artist

Whenever this creature or another creature dies, target player loses 1 life and you gain 1 life.

Captivating Cave

{T}: Add {C}.
{1}, {T}: Add one mana of any color.
{4}, {T}, Sacrifice this land: Put two +1/+1 counters on target creature. Activate only as a sorcery.

Reflections of Littjara

As this enchantment enters, choose a creature type.
Whenever you cast a spell of the chosen type, copy that spell. (A copy of a permanent spell becomes a token.)

Dismal Backwater

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

Sky Diamond

This artifact enters tapped.
{T}: Add {U}.

Rite of Replication

Kicker {5} (You may pay an additional {5} as you cast this spell.)
Create a token that's a copy of target creature. If this spell was kicked, create five of those tokens instead.

Saprazzan Cove

This land enters tapped.
{T}: Put a storage counter on this land.
{T}, Remove any number of storage counters from this land: Add {U} for each storage counter removed this way.

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.)

Flux Channeler

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

Contentious Plan

Deadly Derision

Destroy target creature or planeswalker. Create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

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.)

Clone Legion

For each creature target player controls, create a token that's a copy of that creature.

Murder

Subterranean Hangar

This land enters tapped.
{T}: Put a storage counter on this land.
{T}, Remove any number of storage counters from this land: Add {B} for each storage counter removed this way.

Propaganda

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Spread the Sickness

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

Syr Konrad, the Grim

Whenever another creature dies, or a creature card is put into a graveyard from anywhere other than the battlefield, or a creature card leaves your graveyard, Syr Konrad deals 1 damage to each opponent.
{1}{B}: Each player mills a card. (They each put the top card of their library into their graveyard.)

Command Tower

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.)

Counterpoint

Counter target spell. You may cast a creature, instant, sorcery, or planeswalker spell from your graveyard with mana value less than or equal to that spell's mana value without paying its mana cost.

Black Market

Whenever a creature dies, put a charge counter on this enchantment.
At the beginning of your first main phase, add {B} for each charge counter on this enchantment.

Path of Ancestry

This land enters tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Grave Betrayal

Whenever a creature you don't control dies, return it to the battlefield under your control with an additional +1/+1 counter on it at the beginning of the next end step. That creature is a black Zombie in addition to its other colors and types.

Charcoal Diamond

This artifact enters tapped.
{T}: Add {B}.

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Massacre Wurm

When this creature enters, creatures your opponents control get -2/-2 until end of turn.
Whenever a creature an opponent controls dies, that player loses 2 life.

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.

Revel in Riches

Whenever a creature an opponent controls dies, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")
At the beginning of your upkeep, if you control ten or more Treasures, you win the game.

Everflowing Chalice

Multikicker {2} (You may pay an additional {2} any number of times as you cast this spell.)
This artifact enters with a charge counter on it for each time it was kicked.
{T}: Add {C} for each charge counter on this artifact.

Replicating Ring

{T}: Add one mana of any color.
At the beginning of your upkeep, put a night counter on this artifact. Then if it has eight or more night counters on it, remove all of them and create eight colorless snow artifact tokens named Replicated Ring with "{T}: Add one mana of any color."

Ichthyomorphosis

Enchant creature
Enchanted creature loses all abilities and is a blue Fish with base power and toughness 0/1.

Altar's Reap

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Sludge Monster

Whenever this creature enters or attacks, put a slime counter on up to one other target creature.
Non-Horror creatures with slime counters on them lose all abilities and have base power and toughness 2/2.

Eyes of the Beholder

Target creature gets -11/-11 until end of turn.

Arcane Adaptation

As this enchantment enters, choose a creature type.
Creatures you control are the chosen type in addition to their other types. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.

Island

Slug

Contagion Engine

When this artifact enters, put a -1/-1 counter on each creature target player controls.
{4}, {T}: Proliferate twice. (Choose any number of permanents and/or players, then give each another counter of each kind already there. Then do it again.)

Morkrut Necropod

Menace (This creature can't be blocked except by two or more creatures.)
Whenever this creature attacks or blocks, sacrifice another creature or land.

Endless Evil

Enchant creature you control
At the beginning of your upkeep, create a token that's a copy of enchanted creature, except the token is 1/1.
When enchanted creature dies, if that creature was a Horror, return this card to its owner's hand.

Dreadship Reef

{T}: Add {C}.
{1}, {T}: Put a storage counter on this land.
{1}, Remove X storage counters from this land: Add X mana in any combination of {U} and/or {B}.

Scheming Aspirant

Whenever you proliferate, each opponent loses 2 life and you gain 2 life.

Sand Silos

This land enters tapped.
You may choose not to untap this land during your untap step.
At the beginning of your upkeep, if this land is tapped, put a storage counter on it.
{T}, Remove any number of storage counters from this land: Add {U} for each storage counter removed this way.

Mirror Box

The "legend rule" doesn't apply to permanents you control.
Each legendary creature you control gets +1/+1.
Each nontoken creature you control gets +1/+1 for each other creature you control with the same name as that creature.