Assassin's Trophy

Destroy target permanent an opponent controls. Its controller may search their library for a basic land card, put it onto the battlefield, then shuffle.

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.

Ochran Assassin

Deathtouch
All creatures able to block Ochran Assassin do so.

Switch out?

Ironshell Beetle

When Ironshell Beetle enters, put a +1/+1 counter on target creature.

Necrotic Wound

Undergrowth — Target creature gets -X/-X until end of turn, where X is the number of creature cards in your graveyard. If that creature would die this turn, exile it instead.

Undercity Upheaval

Undergrowth — Distribute X +1/+1 counters among any number of target creatures you control, where X is the number of creature cards in your graveyard as you cast this spell. Creatures you control gain vigilance until end of turn.

Hired Poisoner

Mausoleum Secrets

Undergrowth — Search your library for a black card with mana value less than or equal to the number of creature cards in your graveyard, reveal it, put it into your hand, then shuffle.

Gnarled Grovestrider

Vigilance
Other creatures you control have vigilance.

Dormant Grove

At the beginning of combat on your turn, put a +1/+1 counter on target creature you control. Then if that creature has toughness 6 or greater, transform Dormant Grove.

Dormant Grove // Gnarled Grovestrider

Hatchery Spider

Reach
Undergrowth — When you cast this spell, reveal the top X cards of your library, where X is the number of creature cards in your graveyard. You may put a green permanent card with mana value X or less from among them onto the battlefield. Put the rest on the bottom of your library in a random order.

Vraska's Stoneglare

Destroy target creature. You gain life equal to its toughness. You may search your library and/or graveyard for a card named Vraska, Regal Gorgon, reveal it, and put it into your hand. If you search your library this way, shuffle.

Attendant of Vraska

When Attendant of Vraska dies, if you control a Vraska planeswalker, you gain life equal to Attendant of Vraska's power.

Stony Strength

Put a +1/+1 counter on target creature you control. Untap that creature.

Glaive of the Guildpact

Equipped creature gets +1/+0 for each Gate you control and has vigilance and menace. (A creature with menace can't be blocked except by two or more creatures.)
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Lotleth Giant

Undergrowth — When Lotleth Giant enters, it deals 1 damage to target opponent for each creature card in your graveyard.

Kraul Foragers

Undergrowth — When Kraul Foragers enters, you gain 1 life for each creature card in your graveyard.

Swamp

Silhana Wayfinder

When Silhana Wayfinder enters, look at the top four cards of your library. You may reveal a creature or land card from among them and put it on top of your library. Put the rest on the bottom of your library in a random order.

Vraska, Regal Gorgon

+2: Put a +1/+1 counter on up to one target creature. That creature gains menace until end of turn.
−3: Destroy target creature.
−10: For each creature card in your graveyard, put a +1/+1 counter on each creature you control.

Prey Upon

Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.)

Crawling Infestation

At the beginning of your upkeep, you may mill two cards. (You may put the top two cards of your library into your graveyard.)
Whenever one or more creature cards are put into your graveyard from anywhere during your turn, create a 1/1 green Insect creature token. This ability triggers only once each turn.

Beast Whisperer

Whenever you cast a creature spell, draw a card.

Spinal Centipede

When Spinal Centipede dies, put a +1/+1 counter on target creature you control.

Forest

Atraxa's Fall

Destroy target artifact, battle, enchantment, or creature with flying.

Glowspore Shaman

When Glowspore Shaman enters, mill three cards. You may put a land card from your graveyard on top of your library. (To mill a card, put the top card of your library into your graveyard.)

Vraska the Unseen

+1: Until your next turn, whenever a creature deals combat damage to Vraska the Unseen, destroy that creature.
−3: Destroy target nonland permanent.
−7: Create three 1/1 black Assassin creature tokens with "Whenever this creature deals combat damage to a player, that player loses the game."

Swarm Guildmage

{4}{B}, {T}: Creatures you control get +1/+0 and gain menace until end of turn. (They can't be blocked except by two or more creatures.)
{1}{G}, {T}: You gain 2 life.

Gateway Plaza

Gateway Plaza enters tapped.
When Gateway Plaza enters, sacrifice it unless you pay {1}.
{T}: Add one mana of any color.

Glass of the Guildpact

Multicolored creatures you control get +1/+1.

Golgari Guildgate

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

Spore Crawler

Radiant Fountain

When Radiant Fountain enters, you gain 2 life.
{T}: Add {C}.

Obelisk Spider

Reach
Whenever Obelisk Spider deals combat damage to a creature, put a -1/-1 counter on that creature.
Whenever you put one or more -1/-1 counters on a creature, each opponent loses 1 life and you gain 1 life.

Moss-Pit Skeleton

Kicker {3} (You may pay an additional {3} as you cast this spell.)
If Moss-Pit Skeleton was kicked, it enters with three +1/+1 counters on it.
Whenever one or more +1/+1 counters are put on a creature you control, if Moss-Pit Skeleton is in your graveyard, you may put Moss-Pit Skeleton on top of your library.