Tend the Pests

As an additional cost to cast this spell, sacrifice a creature.
Create X 1/1 black and green Pest creature tokens with "When this creature dies, you gain 1 life," where X is the sacrificed creature's power.

Scurrid Colony

Reach
Scurrid Colony gets +2/+2 as long as you control eight or more lands.

Leech Fanatic

During your turn, Leech Fanatic has lifelink.

Moldering Karok

Ravenous Lindwurm

When Ravenous Lindwurm enters, you gain 4 life.

Guardian Gladewalker

Changeling (This card is every creature type.)
When Guardian Gladewalker enters, put a +1/+1 counter on target creature.

Withercrown

Enchant creature
Enchanted creature has base power 0 and has "At the beginning of your upkeep, you lose 1 life unless you sacrifice this creature."

Bookwurm

Trample
When Bookwurm enters, you gain 3 life and draw a card.
{2}{G}: Put Bookwurm from your graveyard into your library third from the top.

Kazandu Nectarpot

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

Lash of Malice

Target creature gets +2/-2 until end of turn.

Dina, Soul Steeper

Whenever you gain life, each opponent loses 1 life.
{1}, Sacrifice another creature: Dina, Soul Steeper gets +X/+0 until end of turn, where X is the sacrificed creature's power.

Dogged Pursuit

At the beginning of your end step, each opponent loses 1 life and you gain 1 life.

Shessra, Death's Whisper

Bewitching Whispers — When Shessra, Death's Whisper enters, target creature blocks this turn if able.
Whispers of the Grave — At the beginning of your end step, if a creature died this turn, you may pay 2 life. If you do, draw a card.

Witherbloom Campus

Witherbloom Campus enters tapped.
{T}: Add {B} or {G}.
{4}, {T}: Scry 1.

Snakeskin Veil

Put a +1/+1 counter on target creature you control. It gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Big Play

Target creature gets +2/+2 and gains reach until end of turn. Put a +1/+1 counter on it. (A creature with reach can block creatures with flying.)

Might of Murasa

Kicker {2}{G} (You may pay an additional {2}{G} as you cast this spell.)
Target creature gets +3/+3 until end of turn. If this spell was kicked, that creature gets +5/+5 until end of turn instead.

Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.

Hunt for Specimens

Create a 1/1 black and green Pest creature token with "When this creature dies, you gain 1 life."
Learn. (You may reveal a Lesson card you own from outside the game and put it into your hand, or discard a card to draw a card.)

Forest

Slitherbore Pathway

Darkbore Pathway

Darkbore Pathway // Slitherbore Pathway

Woodland Chasm

({T}: Add {B} or {G}.)
Woodland Chasm enters tapped.

Swamp

Daemogoth Woe-Eater

At the beginning of your upkeep, sacrifice a creature.
When you sacrifice Daemogoth Woe-Eater, each opponent discards a card, you draw a card, and you gain 2 life.