Stinging Cave Crawler

Deathtouch
Descend 4 — Whenever this creature attacks, if there are four or more permanent cards in your graveyard, you draw a card and you lose 1 life.

Gluttonous Slug

Menace
Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)

Death Charmer

Whenever this creature deals combat damage to a creature, that creature's controller loses 2 life unless they pay {2}.

Canoptek Scarab Swarm

Flying
Feeder Mandibles — When this creature enters, exile target player's graveyard. For each artifact or land card exiled this way, create a 1/1 colorless Insect artifact creature token with flying.

Mana Skimmer

Flying
Whenever this creature deals damage to a player, tap target land that player controls. That land doesn't untap during its controller's next untap step.

Leech Gauntlet

Lifelink
Equipped creature has lifelink.
Reconfigure {4} ({4}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Eumidian Hatchery

{T}, Pay 1 life: Add {B}. Put a hatchling counter on this land.
When this land is put into a graveyard from the battlefield, for each hatchling counter on it, create a 1/1 black Insect creature token with flying.

Leeching Lurker

Lifelink
Nightbound (If a player casts at least two spells during their own turn, it becomes day next turn.)

Curse of Leeches

Enchant player
As this permanent transforms into Curse of Leeches, attach it to a player.
At the beginning of enchanted player's upkeep, they lose 1 life and you gain 1 life.
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

Curse of Leeches // Leeching Lurker

Fumulus, the Infestation

Flying, deathtouch
Whenever a player sacrifices a nontoken creature, create a 1/1 black Insect creature token with flying.
Whenever an Insect, Leech, Slug, or Worm you control attacks, defending player loses 1 life and you gain 1 life.

Skullslither Worm

When this creature enters, each opponent discards a card. For each opponent who can't, put two +1/+1 counters on this creature.

Balemurk Leech

Eerie — Whenever an enchantment you control enters and whenever you fully unlock a Room, each opponent loses 1 life.

Giant Slug

{5}: At the beginning of your next upkeep, choose a basic land type. This creature gains landwalk of the chosen type until the end of that turn. (It can't be blocked as long as defending player controls a land of that type.)

Gargantuan Leech

This spell costs {1} less to cast for each Cave you control and each Cave card in your graveyard.
Lifelink

Blitz Leech

Flash
When this creature enters, target creature an opponent controls gets -2/-2 until end of turn. Remove all counters from that creature.

Catacomb Slug

Morkrut Necropod

Menace (This creature can't be blocked except by two or more creatures.)
Whenever this creature attacks or blocks, sacrifice another creature or land.

Infestation Sage

When this creature dies, create a 1/1 black and green Insect creature token with flying.

Abundant Maw

Emerge {6}{B} (You may cast this spell by sacrificing a creature and paying the emerge cost reduced by that creature's mana value.)
When you cast this spell, target opponent loses 3 life and you gain 3 life.

Andradite Leech

Black spells you cast cost {B} more to cast.
{B}: This creature gets +1/+1 until end of turn.

Nest of Scarabs

Whenever you put one or more -1/-1 counters on a creature, create that many 1/1 black Insect creature tokens.

Mana Leech

You may choose not to untap this creature during your untap step.
{T}: Tap target land. It doesn't untap during its controller's untap step for as long as this creature remains tapped.

Deadly Grub

Vanishing 3 (This creature enters with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When this creature dies, if it had no time counters on it, create a 6/1 green Insect creature token with shroud. (It can't be the target of spells or abilities.)

Spined Fluke

When this creature enters, sacrifice a creature.
{B}: Regenerate this creature.

Ebony Fly

This artifact enters tapped.
{T}: Add {C}.
{4}: Roll a d6. Until end of turn, you may have this artifact become an X/X Insect artifact creature with flying, where X is the result.
Whenever this artifact attacks, another target attacking creature gains flying until end of turn.

Wriggling Grub

When this creature dies, create two 1/1 black and green Worm creature tokens.

Slimy Dualleech

At the beginning of combat on your turn, target creature you control with power 2 or less gets +1/+0 and gains deathtouch until end of turn.

Swamp

Festerleech

Whenever this creature deals combat damage to a player, you mill two cards.
{1}{B}: This creature gets +2/+2 until end of turn. Activate only once each turn.

Insidious Bookworms

When this creature dies, you may pay {1}{B}. If you do, target player discards a card at random.

Mole Worms

Squelching Leeches

Squelching Leeches's power and toughness are each equal to the number of Swamps you control.