Biomathematician

When this creature enters, create a 0/0 green and blue Fractal creature token. Put a +1/+1 counter on each Fractal you control.

Thrive

Put a +1/+1 counter on each of X target creatures.

Citanul Druid

Whenever an opponent casts an artifact spell, put a +1/+1 counter on this creature.

Forced Adaptation

Enchant creature
At the beginning of your upkeep, put a +1/+1 counter on enchanted creature.

Battlegrowth

Hunger of the Howlpack

Put a +1/+1 counter on target creature.
Morbid — Put three +1/+1 counters on that creature instead if a creature died this turn.

Elvish Vanguard

Whenever another Elf enters, put a +1/+1 counter on this creature.

Fractal Summoning

Create a 0/0 green and blue Fractal creature token. Put X +1/+1 counters on it.

Deepwood Denizen

Vigilance (Attacking doesn't cause this creature to tap.)
{5}{G}, {T}: Draw a card. This ability costs {1} less to activate for each +1/+1 counter on creatures you control.

Scale the Heights

Put a +1/+1 counter on up to one target creature. You gain 2 life. You may play an additional land this turn.
Draw a card.

Servant of the Scale

This creature enters with a +1/+1 counter on it.
When this creature dies, put X +1/+1 counters on target creature you control, where X is the number of +1/+1 counters on this creature.

Ivy Elemental

This creature enters with X +1/+1 counters on it.

Quarry Hauler

When this creature enters, for each kind of counter on target permanent, put another counter of that kind on it or remove one from it.

Gnarlid Pack

Multikicker {1}{G} (You may pay an additional {1}{G} any number of times as you cast this spell.)
This creature enters with a +1/+1 counter on it for each time it was kicked.

Primal Cocoon

Enchant creature
At the beginning of your upkeep, put a +1/+1 counter on enchanted creature.
When enchanted creature attacks or blocks, sacrifice this Aura.

Territorial Scythecat

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Landfall — Whenever a land you control enters, put a +1/+1 counter on this creature.

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.)

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.

Duskshell Crawler

When this creature enters, put a +1/+1 counter on target creature.
Each creature you control with a +1/+1 counter on it has trample. (It can deal excess combat damage to the player or planeswalker it's attacking.)

Gnoll Hunter

Pack tactics — Whenever this creature attacks, if you attacked with creatures with total power 6 or greater this combat, put a +1/+1 counter on this creature.

Big Play

Target creature gets +2/+2 and gains reach until end of turn. Put a +1/+1 counter on it. (A creature with reach can block creatures with flying.)

Avoid Fate

Counter target instant or Aura spell that targets a permanent you control.

Bioshift

Move any number of +1/+1 counters from target creature onto another target creature with the same controller.

Strength of Solidarity

Choose target creature you control. Put a +1/+1 counter on it for each creature in your party. (Your party consists of up to one each of Cleric, Rogue, Warrior, and Wizard.)

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.)

Advocate of the Beast

At the beginning of your end step, put a +1/+1 counter on target Beast creature you control.

Predatory Hunger

Enchant creature
Whenever an opponent casts a creature spell, put a +1/+1 counter on enchanted creature.

Mutant's Prey

Target creature you control with a +1/+1 counter on it fights target creature an opponent controls. (Each deals damage equal to its power to the other.)

Titanic Brawl

This spell costs {1} less to cast if it targets a creature you control with a +1/+1 counter on it.
Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.)

Fertilid

This creature enters with two +1/+1 counters on it.
{1}{G}, Remove a +1/+1 counter from this creature: Target player searches their library for a basic land card, puts it onto the battlefield tapped, then shuffles.

New Horizons

Enchant land
When this Aura enters, put a +1/+1 counter on target creature you control.
Enchanted land has "{T}: Add two mana of any one color."

Jade Bearer

When this creature enters, put a +1/+1 counter on another target Merfolk you control.

Guardian Gladewalker

Changeling (This card is every creature type.)
When this creature enters, put a +1/+1 counter on target creature.

Crowned Ceratok

Trample
Each creature you control with a +1/+1 counter on it has trample.

Gnarlid Colony

Kicker {2}{G} (You may pay an additional {2}{G} as you cast this spell.)
If this creature was kicked, it enters with two +1/+1 counters on it.
Each creature you control with a +1/+1 counter on it has trample. (It can deal excess combat damage to the player or planeswalker it's attacking.)

Oran-Rief Survivalist

Whenever this creature or another Ally you control enters, you may put a +1/+1 counter on this creature.

Ferocity

Enchant creature
Whenever enchanted creature blocks or becomes blocked, you may put a +1/+1 counter on it.

Duel for Dominance

Coven — Choose target creature you control and target creature you don't control. If you control three or more creatures with different powers, put a +1/+1 counter on the chosen creature you control. Then the chosen creatures fight each other. (Each deals damage equal to its power to the other.)

Elvish Handservant

Whenever a player casts a Giant spell, you may put a +1/+1 counter on this creature.