Demonic Vigor

Enchant creature
Enchanted creature gets +1/+1.
When enchanted creature dies, return that card to its owner's hand.

Genesis Chamber

Whenever a nontoken creature enters, if Genesis Chamber is untapped, that creature's controller creates a 1/1 colorless Myr artifact creature token.

Thallid Omnivore

{1}, Sacrifice another creature: Thallid Omnivore gets +2/+2 until end of turn. If a Saproling was sacrificed this way, you gain 2 life.

Overgrown Armasaur

Enrage — Whenever Overgrown Armasaur is dealt damage, create a 1/1 green Saproling creature token.

Golgari Findbroker

When Golgari Findbroker enters, return target permanent card from your graveyard to your hand.

Kraul Harpooner

Reach
Undergrowth — When Kraul Harpooner enters, choose up to one target creature you don't control with flying. Kraul Harpooner gets +X/+0 until end of turn, where X is the number of creature cards in your graveyard, then you may have Kraul Harpooner fight that creature.

Sporecrown Thallid

Each other creature you control that's a Fungus or Saproling gets +1/+1.

Saproling Migration

Kicker {4} (You may pay an additional {4} as you cast this spell.)
Create two 1/1 green Saproling creature tokens. If this spell was kicked, create four of those tokens instead.

Druid of the Cowl

Cast Down

Leyline Prowler

Deathtouch, lifelink
{T}: Add one mana of any color.

Siege Wurm

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Trample

Vigorspore Wurm

Undergrowth — When Vigorspore Wurm enters, target creature gains vigilance and gets +X/+X until end of turn, where X is the number of creature cards in your graveyard.
Vigorspore Wurm can't be blocked by more than one creature.

Grapple with the Past

Mill three cards, then you may return a creature or land card from your graveyard to your hand. (To mill three cards, put the top three cards of your library into your graveyard.)

Song of Freyalise

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Until your next turn, creatures you control gain "{T}: Add one mana of any color."
III — Put a +1/+1 counter on each creature you control. Those creatures gain vigilance, trample, and indestructible until end of turn.

Swarm of Bloodflies

Flying
Swarm of Bloodflies enters with two +1/+1 counters on it.
Whenever another creature dies, put a +1/+1 counter on Swarm of Bloodflies.

Deathbloom Thallid

When Deathbloom Thallid dies, create a 1/1 green Saproling creature token.

Springleaf Drum

{T}, Tap an untapped creature you control: Add one mana of any color.

Paradise Druid

This creature has hexproof as long as it's untapped. (It can't be the target of spells or abilities your opponents control.)
{T}: Add one mana of any color.

Spore Swarm

Create three 1/1 green Saproling creature tokens.

Slimefoot, the Stowaway

Whenever a Saproling you control dies, Slimefoot, the Stowaway deals 1 damage to each opponent and you gain 1 life.
{4}: Create a 1/1 green Saproling creature token.

Forest

Swamp

Slum Reaper

When Slum Reaper enters, each player sacrifices a creature of their choice.

Thallid Soothsayer

Golgari Guildgate

This land enters tapped.
{T}: Add {B} or {G}.

Yavimaya Sapherd

When Yavimaya Sapherd enters, create a 1/1 green Saproling creature token.

Rhizome Lurcher

Undergrowth — Rhizome Lurcher enters with a number of +1/+1 counters on it equal to the number of creature cards in your graveyard.

Bloodbriar

Whenever you sacrifice another permanent, put a +1/+1 counter on Bloodbriar.

Quest for the Gravelord

Whenever a creature dies, you may put a quest counter on Quest for the Gravelord.
Remove three quest counters from Quest for the Gravelord and sacrifice it: Create a 5/5 black Zombie Giant creature token.