Steady Progress

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

Vraska's Fall

Each opponent sacrifices a creature or planeswalker of their choice and gets a poison counter.

Scion of Halaster

Commander creatures you own have "The first time you would draw a card each turn, instead look at the top two cards of your library. Put one of them into your graveyard and the other back on top of your library. Then draw a card."

Chromatic Sphere

{1}, {T}, Sacrifice this artifact: Add one mana of any color. Draw a card.

Dismiss

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.

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.)

Contradict

Sol Ring

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.)

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.)

Disentomb

Return target creature card from your graveyard to your hand.

Sunken Hollow

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

Memory Drain

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.)

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.)

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.)

Submerged Boneyard

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

Crypt Lurker

When this creature enters, you may sacrifice a creature or discard a creature card. If you do, draw a card.

Tattered Mummy

When this creature dies, each opponent loses 2 life.

Launch Mishap

Counter target creature or planeswalker spell. Create a 1/1 colorless Thopter artifact creature token with flying.

Gloom Sower

Whenever this creature becomes blocked by a creature, that creature's controller loses 2 life and you gain 2 life.

Jwar Isle Refuge

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

Vexing Radgull

Flying
Whenever this creature deals combat damage to a player, that player gets two rad counters if they don't have any rad counters. Otherwise, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

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.)

Kiora's Dambreaker

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

Dimir Guildgate

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.)

Voidwing Hybrid

Flying
Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
When you proliferate, return this card from your graveyard to your hand.

Darksteel Ingot

Indestructible (Effects that say "destroy" don't destroy this artifact.)
{T}: Add one mana of any color.

Failed Inspection

Counter target spell. Draw a card, then discard a card.

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.)

Fervent Denial

Counter target spell.
Flashback {5}{U}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Decanter of Endless Water

You have no maximum hand size.
{T}: Add one mana of any color.

Scavenging Harpy

Flying
When this creature enters, exile target card from an opponent's graveyard.

The Darkness Crystal

Black spells you cast cost {1} less to cast.
If a nontoken creature an opponent controls would die, instead exile it and you gain 2 life.
{4}{B}{B}, {T}: Put target creature card exiled with The Darkness Crystal onto the battlefield tapped under your control with two additional +1/+1 counters on it.

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.)

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.)

Swamp

Command Tower

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

Gulping Scraptrap

When this creature enters or dies, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

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.)

Celestial Prism

Catacomb Crocodile

Core Prowler

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
When this creature dies, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Venser, Corpse Puppet

Lifelink, toxic 1
Whenever you proliferate, choose one —
• If you don't control a creature named The Hollow Sentinel, create The Hollow Sentinel, a legendary 3/3 colorless Phyrexian Golem artifact creature token.
• Target artifact creature you control gains flying and lifelink until end of turn.

Sorcerer of the Fang

{5}{B}, {T}: This creature deals 2 damage to target opponent or planeswalker.

Vampire Opportunist

{6}{B}: Each opponent loses 2 life and you gain 2 life.

Bone to Ash

Counter target creature spell.
Draw a card.

Arcane Signet

Recon Craft Theta

Flying
When this Vehicle enters, create a 0/0 blue Alien creature token. Put a +1/+1 counter on it.
Whenever this Vehicle attacks, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Crew 2

Mesmerizing Dose

Enchant creature
When this Aura enters, tap enchanted creature, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Enchanted creature doesn't untap during its controller's untap step.

Whisper of the Dross

Target creature gets -1/-1 until end of turn. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Vat Emergence

Put target creature card from a graveyard onto the battlefield under your control. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Chromatic Star

{1}, {T}, Sacrifice this artifact: Add one mana of any color.
When this artifact is put into a graveyard from the battlefield, draw a card.

Island

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.)

Soulreaper of Mogis

{2}{B}, Sacrifice a creature: Draw a card.

Contract Killing

Destroy target creature. Create two Treasure tokens. (They're artifacts with "{T}, Sacrifice this token: Add one mana of any color.")

Mutual Destruction

This spell has flash as long as you control a permanent with flash.
As an additional cost to cast this spell, sacrifice a creature.
Destroy 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.)

Grave Peril

When a nonblack creature enters, sacrifice this enchantment. If you do, destroy that creature.

Scheming Aspirant

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

Slimebind

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Enchanted creature gets -4/-0.

Morbid Opportunist

Whenever one or more other creatures die, draw a card. This ability triggers only once each turn.

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.)

Whisper Squad

{1}{B}: Search your library for a card named Whisper Squad, put it onto the battlefield tapped, then shuffle.