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.

Have

Echoing Truth

Return target nonland permanent and all other permanents with the same name as that permanent to their owners' hands.

Thornwood Falls

Thornwood Falls enters tapped.
When Thornwood Falls enters, you gain 1 life.
{T}: Add {G} or {U}.

Brainstorm

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

Keep Safe

Counter target spell that targets a permanent you control.
Draw a card.

Island

Silhana Ledgewalker

Hexproof (This creature can't be the target of spells or abilities your opponents control.)
Silhana Ledgewalker can't be blocked except by creatures with flying.

Evolving Wilds

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

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.

Ram Through

Target creature you control deals damage equal to its power to target creature you don't control. If the creature you control has trample, excess damage is dealt to that creature's controller instead.

Forest

Mysterious Egg

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

Essence Symbiote

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

Almighty Brushwagg

Trample
{3}{G}: Almighty Brushwagg gets +3/+3 until end of turn.

Slippery Bogle

Hexproof (This creature can't be the target of spells or abilities your opponents control.)