Mysterious Egg

Whenever this creature mutates, put a +1/+1 counter on it.

Island

Migratory Greathorn

Mutate {2}{G} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Whenever this creature mutates, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Ponder

Look at the top three cards of your library, then put them back in any order. You may shuffle.
Draw a card.

Vulpikeet

Mutate {2}{W} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Flying
Whenever this creature mutates, put a +1/+1 counter on it.

Blossoming Sands

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

Dreamtail Heron

Mutate {3}{U} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Flying
Whenever this creature mutates, draw a card.

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Essence Symbiote

Whenever a creature you control mutates, put a +1/+1 counter on that creature and you gain 2 life.

Forest

Thornwood Falls

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

Evolving Wilds

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Tranquil Cove

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

Lagonna-Band Trailblazer

Heroic — Whenever you cast a spell that targets Lagonna-Band Trailblazer, put a +1/+1 counter on Lagonna-Band Trailblazer.

Kor Skyfisher

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