Bloated Contaminator

Trample
Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
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.)

Surge Conductor

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

Cankerbloom

{1}, Sacrifice this creature: Choose one —
• Destroy target artifact.
• Destroy target enchantment.
• Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Loam Dryad

{T}, Tap an untapped creature you control: Add one mana of any color.

Honored Hierarch

Renown 1 (When this creature deals combat damage to a player, if it isn't renowned, put a +1/+1 counter on it and it becomes renowned.)
As long as this creature is renowned, it has vigilance and "{T}: Add one mana of any color."

Smell Fear

Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Target creature you control fights up to one target creature you don't control.

Fyndhorn Elves

Boreal Druid

Elvish Mystic

Adaptive Sporesinger

Vigilance
When this creature enters, choose one —
• Target creature gets +2/+2 and gains vigilance until end of turn.
• 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.

Saruli Caretaker

Defender
{T}, Tap an untapped creature you control: Add one mana of any color.

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.)

Ambush Viper

Copper Longlegs

Reach
{1}{G}, Sacrifice this creature: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Unnatural Restoration

Return target permanent card from your graveyard to your hand. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Jaspera Sentinel

Reach
{T}, Tap an untapped creature you control: Add one mana of any color.

Tromell, Seymour's Butler

Each other nontoken creature you control enters with an additional +1/+1 counter on it.
{1}, {T}: Proliferate X times, where X is the number of nontoken creatures you control that entered this turn. (To proliferate, choose any number of permanents and/or players, then give each another counter of each kind already there.)

Ixalli's Lorekeeper

{T}: Add one mana of any color. Spend this mana only to cast a Dinosaur spell or activate an ability of a Dinosaur source.

Contaminant Grafter

Trample, toxic 1
Whenever one or more creatures you control deal combat damage to one or more players, proliferate.
Corrupted — At the beginning of your end step, if an opponent has three or more poison counters, draw a card, then you may put a land card from your hand onto the battlefield.

Expand the Sphere

Look at the top six cards of your library. Put up to two land cards from among them onto the battlefield tapped and the rest on the bottom of your library in a random order. If you put fewer than two lands onto the battlefield this way, proliferate a number of times equal to the difference. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Sol Ring

Birds of Paradise

Delighted Halfling

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a legendary spell, and that spell can't be countered.

Courage in Crisis

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.)

Ohran Frostfang

Attacking creatures you control have deathtouch.
Whenever a creature you control deals combat damage to a player, draw a card.

Llanowar Elves

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.)

Bloom Hulk

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

Citanul Stalwart

{T}, Tap an untapped artifact or creature you control: Add one mana of any color.

Fynn, the Fangbearer

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Whenever a creature you control with deathtouch deals combat damage to a player, that player gets two poison counters. (A player with ten or more poison counters loses the game.)

Pollenbright Druid

When this creature enters, choose one —
• Put a +1/+1 counter on target creature.
• Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Gilded Goose

Flying
When this creature enters, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
{1}{G}, {T}: Create a Food token.
{T}, Sacrifice a Food: Add one mana of any color.

Saryth, the Viper's Fang

Other tapped creatures you control have deathtouch.
Other untapped creatures you control have hexproof.
{1}, {T}: Untap another target creature or land you control.

Forest

Heritage Druid

Tap three untapped Elves you control: Add {G}{G}{G}.

Venerated Rotpriest

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
Whenever a creature you control becomes the target of a spell, target opponent gets a poison counter.

Gene Pollinator

{T}, Tap an untapped permanent you control: Add one mana of any color.

Arbor Elf

Bow of Nylea

Attacking creatures you control have deathtouch.
{1}{G}, {T}: Choose one —
• Put a +1/+1 counter on target creature.
• Bow of Nylea deals 2 damage to target creature with flying.
• You gain 3 life.
• Put up to four target cards from your graveyard on the bottom of your library in any order.

Contagious Vorrac

When this creature enters, look at the top four cards of your library. You may reveal a land card from among them and put it into your hand. Put the rest on the bottom of your library in a random order. If you didn't put a card into your hand this way, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

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}

Glistening Sphere

This artifact enters tapped.
When this artifact enters, proliferate.
{T}: Add one mana of any color.
Corrupted — {T}: Add three mana of any one color. Activate only if an opponent has three or more poison counters.

Park Heights Maverick

Dethrone (Whenever this creature attacks the player with the most life or tied for the most life, put a +1/+1 counter on it.)
This creature can't be blocked by creatures with power 2 or less.
Whenever this creature deals combat damage to a player or dies, proliferate.

Carnivorous Canopy

Destroy target artifact, enchantment, or creature with flying. If that permanent'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.)