Essence Warden

Whenever another creature enters, you gain 1 life.

Primordial Sage

Whenever you cast a creature spell, you may draw a card.

Lifecrafter's Bestiary

At the beginning of your upkeep, scry 1.
Whenever you cast a creature spell, you may pay {G}. If you do, draw a card.

Elvish Eulogist

Sacrifice Elvish Eulogist: You gain 1 life for each Elf card in your graveyard.

Jade Bearer

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

Beastcaller Savant

Haste
{T}: Add one mana of any color. Spend this mana only to cast a creature spell.

Soul of the Harvest

Trample
Whenever another nontoken creature you control enters, you may draw a card.

Beast Whisperer

Whenever you cast a creature spell, draw a card.

Sachi, Daughter of Seshiro

Other Snake creatures you control get +0/+1.
Shamans you control have "{T}: Add {G}{G}."

Nurturer Initiate

Whenever a player casts a green spell, you may pay {1}. If you do, target creature gets +1/+1 until end of turn.

Skyshroud Claim

Search your library for up to two Forest cards, put them onto the battlefield, then shuffle.

Llanowar Augur

Sacrifice Llanowar Augur: Target creature gets +3/+3 and gains trample until end of turn. Activate only during your upkeep.

Kumena's Speaker

Kumena's Speaker gets +1/+1 as long as you control another Merfolk or an Island.

Collective Unconscious

Draw a card for each creature you control.

Sol Ring

Centaur Omenreader

As long as Centaur Omenreader is tapped, creature spells you cast cost {2} less to cast.

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Shamanic Revelation

Draw a card for each creature you control.
Ferocious — You gain 4 life for each creature you control with power 4 or greater.

Harmonize

Cultivate

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Martyr of Spores

{1}, Reveal X green cards from your hand, Sacrifice Martyr of Spores: Target creature gets +X/+X until end of turn.