Kor Skyfisher

Flying
When Kor Skyfisher enters, return a permanent you control to its owner's hand.

Pridemalkin

When Pridemalkin enters, put a +1/+1 counter on target creature you control.
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.)

Duskshell Crawler

When Duskshell Crawler 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.)

Heir of the Ancient Fang

Heir of the Ancient Fang enters with a +1/+1 counter on it if you control a modified creature. (Equipment, Auras you control, and counters are modifications.)

Elvish Visionary

When Elvish Visionary enters, draw a card.

Shaman of Spring

When Shaman of Spring enters, draw a card.

Rhox Oracle

Spike Drone

Spike Drone enters with a +1/+1 counter on it.
{2}, Remove a +1/+1 counter from Spike Drone: Put a +1/+1 counter on target creature.

Aquastrand Spider

Graft 2 (This creature enters with two +1/+1 counters on it. Whenever another creature enters, you may move a +1/+1 counter from this creature onto it.)
{G}: Target creature with a +1/+1 counter on it gains reach until end of turn. (It can block creatures with flying.)

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.

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.)

Spike Colony

Spike Colony enters with four +1/+1 counters on it.
{2}, Remove a +1/+1 counter from Spike Colony: Put a +1/+1 counter on target creature.

Scrounging Bandar

Scrounging Bandar enters with two +1/+1 counters on it.
At the beginning of your upkeep, you may move any number of +1/+1 counters from Scrounging Bandar onto another target creature.

Arcbound Hybrid

Haste
Modular 2 (This creature enters with two +1/+1 counters on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

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.

Hamza, Guardian of Arashin

This spell costs {1} less to cast for each creature you control with a +1/+1 counter on it.
Creature spells you cast cost {1} less to cast for each creature you control with a +1/+1 counter on it.

Ivy Elemental

Ivy Elemental enters with X +1/+1 counters on it.

Feat of Resistance

Put a +1/+1 counter on target creature you control. It gains protection from the color of your choice until end of turn. (It can't be blocked, targeted, dealt damage, enchanted, or equipped by anything of that color.)

Ancient Animus

Put a +1/+1 counter on target creature you control if it's legendary. Then it fights target creature an opponent controls. (Each deals damage equal to its power to the other.)

Ambush Krotiq

Trample
When Ambush Krotiq enters, return another creature you control to its owner's hand.

Forest

Fertilid

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

Phantom Tiger

Phantom Tiger enters with two +1/+1 counters on it.
If damage would be dealt to Phantom Tiger, prevent that damage. Remove a +1/+1 counter from Phantom Tiger.

Papercraft Decoy

When Papercraft Decoy leaves the battlefield, you may pay {2}. If you do, draw a card.

Arcbound Stinger

Flying
Modular 1 (This creature enters with a +1/+1 counter on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Phantom Nomad

Phantom Nomad enters with two +1/+1 counters on it.
If damage would be dealt to Phantom Nomad, prevent that damage. Remove a +1/+1 counter from Phantom Nomad.

Clockwork Beetle

Clockwork Beetle enters with two +1/+1 counters on it.
Whenever Clockwork Beetle attacks or blocks, remove a +1/+1 counter from it at end of combat.

Guardians of Koilos

When Guardians of Koilos enters, you may return another target historic permanent you control to its owner's hand. (Artifacts, legendaries, and Sagas are historic.)

Frontier Mastodon

Ferocious — Frontier Mastodon enters with a +1/+1 counter on it if you control a creature with power 4 or greater.

Skyscanner

Flying
When Skyscanner enters, draw a card.

Carrier Pigeons

Flying
When Carrier Pigeons enters, draw a card at the beginning of the next turn's upkeep.

Arcbound Bruiser

Modular 3 (This creature enters with three +1/+1 counters on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Inspiring Overseer

Flying
When Inspiring Overseer enters, you gain 1 life and draw a card.

Cytospawn Shambler

Graft 6 (This creature enters with six +1/+1 counters on it. Whenever another creature enters, you may move a +1/+1 counter from this creature onto it.)
{G}: Target creature with a +1/+1 counter on it gains trample until end of turn.

Clockwork Condor

Flying
Clockwork Condor enters with three +1/+1 counters on it.
Whenever Clockwork Condor attacks or blocks, remove a +1/+1 counter from it at end of combat.

Invasive Species

When Invasive Species enters, return another permanent you control to its owner's hand.

Undergrowth Scavenger

Undergrowth Scavenger enters with a number of +1/+1 counters on it equal to the number of creature cards in all graveyards.

Guardian Kirin

Flying
Whenever another creature you control dies, put a +1/+1 counter on Guardian Kirin.

Spike Worker

Spike Worker enters with two +1/+1 counters on it.
{2}, Remove a +1/+1 counter from Spike Worker: Put a +1/+1 counter on target creature.

Golem Foundry

Whenever you cast an artifact spell, you may put a charge counter on Golem Foundry.
Remove three charge counters from Golem Foundry: Create a 3/3 colorless Golem artifact creature token.

Priest of Ancient Lore

When Priest of Ancient Lore enters, you gain 1 life and draw a card.

Iron Apprentice

Iron Apprentice enters with a +1/+1 counter on it.
When Iron Apprentice dies, if it had counters on it, put those counters on target creature you control.

Ainok Bond-Kin

Outlast {1}{W} ({1}{W}, {T}: Put a +1/+1 counter on this creature. Outlast only as a sorcery.)
Each creature you control with a +1/+1 counter on it has first strike.

Lifecraft Cavalry

Trample
Revolt — Lifecraft Cavalry enters with two +1/+1 counters on it if a permanent you controlled left the battlefield this turn.

Filigree Familiar

When Filigree Familiar enters, you gain 2 life.
When Filigree Familiar dies, draw a card.

Bond Beetle

When Bond Beetle enters, put a +1/+1 counter on target creature.

Yavimaya Elder

When Yavimaya Elder dies, you may search your library for up to two basic land cards, reveal them, put them into your hand, then shuffle.
{2}, Sacrifice Yavimaya Elder: Draw a card.

Rhox Meditant

When Rhox Meditant enters, if you control a green permanent, draw a card.

Caldaia Strongarm

When Caldaia Strongarm enters, put two +1/+1 counters on target creature.
Blitz {3}{G} (If you cast this spell for its blitz cost, it gains haste and "When this creature dies, draw a card." Sacrifice it at the beginning of the next end step.)

Whitemane Lion

Flash
When Whitemane Lion enters, return a creature you control to its owner's hand.

Ancestral Statue

When Ancestral Statue enters, return a nonland permanent you control to its owner's hand.

Kronch Wrangler

Trample
Whenever a creature you control with power 4 or greater enters, put a +1/+1 counter on Kronch Wrangler.

Generous Stray

Celebrity Fencer

Alliance — Whenever another creature you control enters, put a +1/+1 counter on Celebrity Fencer.

Arcbound Prototype

Modular 2 (This creature enters with two +1/+1 counters on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Plains

Frostweb Spider

Reach (This creature can block creatures with flying.)
Whenever Frostweb Spider blocks a creature with flying, put a +1/+1 counter on Frostweb Spider at end of combat.

Arcbound Worker

Modular 1 (This creature enters with a +1/+1 counter on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Arcbound Mouser

Lifelink
Modular 1 (This creature enters with a +1/+1 counter on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Joraga Visionary

When Joraga Visionary enters, draw a card.

Wirewood Savage

Whenever a Beast enters, you may draw a card.

Citanul Woodreaders

Kicker {2}{G} (You may pay an additional {2}{G} as you cast this spell.)
When Citanul Woodreaders enters, if it was kicked, draw two cards.

Llanowar Visionary

When Llanowar Visionary enters, draw a card.
{T}: Add {G}.

Shinewend

Flying
Shinewend enters with a +1/+1 counter on it.
{1}{W}, Remove a +1/+1 counter from Shinewend: Destroy target enchantment.