Lashwrithe

Living weapon (When this Equipment enters, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)
Equipped creature gets +1/+1 for each Swamp you control.
Equip {B/P}{B/P} ({B/P} can be paid with either {B} or 2 life.)

Quag Sickness

Enchant creature
Enchanted creature gets -1/-1 for each Swamp you control.

Squelching Leeches

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

Dread Presence

Whenever a Swamp you control enters, choose one —
• You draw a card and you lose 1 life.
• Dread Presence deals 2 damage to any target and you gain 2 life.

Insatiable Harpy

Diabolic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Phyrexian Rager

When Phyrexian Rager enters, you draw a card and you lose 1 life.

Marang River Skeleton

{B}: Regenerate Marang River Skeleton.
Megamorph {3}{B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its megamorph cost and put a +1/+1 counter on it.)

Defile

Target creature gets -1/-1 until end of turn for each Swamp you control.

Carrion Wall

Defender (This creature can't attack.)
{1}{B}: Regenerate Carrion Wall.

Duress

Target opponent reveals their hand. You choose a noncreature, nonland card from it. That player discards that card.

Barren Moor

Barren Moor enters tapped.
{T}: Add {B}.
Cycling {B} ({B}, Discard this card: Draw a card.)

Corrupt

Corrupt deals damage to any target equal to the number of Swamps you control. You gain life equal to the damage dealt this way.

Corpulent Corpse

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
Suspend 5—{B} (Rather than cast this card from your hand, you may pay {B} and exile it with five time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost. It has haste.)

Twisted Abomination

{B}: Regenerate Twisted Abomination. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)
Swampcycling {2} ({2}, Discard this card: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.)

Read the Bones

Scry 2, then draw two cards. You lose 2 life. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Grave Exchange

Return target creature card from your graveyard to your hand. Target player sacrifices a creature of their choice.

Liliana of the Dark Realms

+1: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.
−3: Target creature gets +X/+X or -X/-X until end of turn, where X is the number of Swamps you control.
−6: You get an emblem with "Swamps you control have '{T}: Add {B}{B}{B}{B}.'"

Tooth Collector

When Tooth Collector enters, target creature an opponent controls gets -1/-1 until end of turn.
Delirium — At the beginning of each opponent's upkeep, if there are four or more card types among cards in your graveyard, target creature that player controls gets -1/-1 until end of turn.

Sanguine Guard

First strike
{1}{B}: Regenerate Sanguine Guard.

Mutilate

All creatures get -1/-1 until end of turn for each Swamp you control.

Restless Dead

Reassembling Skeleton

{1}{B}: Return this card from your graveyard to the battlefield tapped.

Mind Sludge

Target player discards a card for each Swamp you control.

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Nantuko Shade

{B}: Nantuko Shade gets +1/+1 until end of turn.

Phyrexian Gargantua

When Phyrexian Gargantua enters, you draw two cards and you lose 2 life.

Giant Scorpion

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Keepsake Gorgon

Deathtouch
{5}{B}{B}: Monstrosity 1. (If this creature isn't monstrous, put a +1/+1 counter on it and it becomes monstrous.)
When Keepsake Gorgon becomes monstrous, destroy target non-Gorgon creature an opponent controls.

Crypt Ripper

Haste
{B}: Crypt Ripper gets +1/+1 until end of turn.

Consume Spirit

Spend only black mana on X.
Consume Spirit deals X damage to any target and you gain X life.

Dark Banishing

Destroy target nonblack creature. It can't be regenerated.

Swamp

Walking Atlas

{T}: You may put a land card from your hand onto the battlefield.

Grasp of Darkness

Target creature gets -4/-4 until end of turn.

Tendrils of Corruption

Tendrils of Corruption deals X damage to target creature and you gain X life, where X is the number of Swamps you control.

Spawning Pool

Spawning Pool enters tapped.
{T}: Add {B}.
{1}{B}: Spawning Pool becomes a 1/1 black Skeleton creature with "{B}: Regenerate this creature" until end of turn. It's still a land. (If it regenerates, the next time it would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)