Fearless Fledgling

Landfall — Whenever a land you control enters, put a +1/+1 counter on this creature. It gains flying until end of turn.

Sunscape Familiar

Defender (This creature can't attack.)
Green spells and blue spells you cast cost {1} less to cast.

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.)

Birds of Paradise

Gyre Sage

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.)
{T}: Add {G} for each +1/+1 counter on this creature.

Tatyova, Benthic Druid

Landfall — Whenever a land you control enters, you gain 1 life and draw a card.

Deepglow Skate

When this creature enters, double the number of each kind of counter on any number of target permanents.

Pridemalkin

When this creature 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.)

Growth Spiral

Draw a card. You may put a land card from your hand onto the battlefield.

Chulane, Teller of Tales

Vigilance
Whenever you cast a creature spell, draw a card, then you may put a land card from your hand onto the battlefield.
{3}, {T}: Return target creature you control to its owner's hand.

Ascendant Packleader

This creature enters with a +1/+1 counter on it if you control a permanent with mana value 4 or greater.
Whenever you cast a spell with mana value 4 or greater, put a +1/+1 counter on this creature.

Lotus Cobra

Landfall — Whenever a land you control enters, add one mana of any color.

Noble Hierarch

Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)
{T}: Add {G}, {W}, or {U}.

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."

Scute Mob

At the beginning of your upkeep, if you control five or more lands, put four +1/+1 counters on this creature.

Kalonian Hydra

Trample
This creature enters with four +1/+1 counters on it.
Whenever this creature attacks, double the number of +1/+1 counters on each creature you control.

Forgotten Ancient

Whenever a player casts a spell, you may put a +1/+1 counter on this creature.
At the beginning of your upkeep, you may move any number of +1/+1 counters from this creature onto other creatures.

Panharmonicon

If an artifact or creature entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Prowling Felidar

Vigilance
Landfall — Whenever a land you control enters, put a +1/+1 counter on this creature.

Juniper Order Ranger

Whenever another creature you control enters, put a +1/+1 counter on that creature and a +1/+1 counter on this creature.

Wall of Blossoms

Defender
When this creature enters, draw a card.

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.