Contaminated Bond

Enchant creature (Target a creature as you cast this. This card enters attached to that creature.)
Whenever enchanted creature attacks or blocks, its controller loses 3 life.

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.

Unhallowed Pact

Enchant creature
When enchanted creature dies, return that card to the battlefield under your control.

Vorrac Battlehorns

Equipped creature has trample and can't be blocked by more than one creature.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery. This card enters unattached and stays on the battlefield if the creature leaves.)

Yargle, Glutton of Urborg

Go for the Throat

Dune Beetle

Tainted Strike

Target creature gets +1/+0 and gains infect until end of turn. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Necromancer's Magemark

Enchant creature
Creatures you control that are enchanted get +1/+1.
If a creature you control that's enchanted would die, return it to its owner's hand instead.

Rotting Mastodon

Evil Presence

Wandering Tombshell

Prying Blade

Equipped creature gets +1/+0.
Whenever equipped creature deals combat damage to a player, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Supernatural Stamina

Until end of turn, target creature gets +2/+0 and gains "When this creature dies, return it to the battlefield tapped under its owner's control."

Bubbling Muck

Until end of turn, whenever a player taps a Swamp for mana, that player adds an additional {B}.

Explorer's Scope

Whenever equipped creature attacks, look at the top card of your library. If it's a land card, you may put it onto the battlefield tapped.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Bonesplitter

Catacomb Slug

Dragon Shadow

Enchant creature
Enchanted creature gets +1/+0 and has fear. (It can't be blocked except by artifact creatures and/or black creatures.)
When a creature with mana value 6 or greater enters, you may return Dragon Shadow from your graveyard to the battlefield attached to that creature.

Blood Curdle

Destroy target creature. Put a menace counter on a creature you control. (It can't be blocked except by two or more creatures.)

Giant Cockroach

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.

Syphon Mind

Each other player discards a card. You draw a card for each card discarded this way.

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.

Python

Nether Horror

Cranial Plating

Equipped creature gets +1/+0 for each artifact you control.
{B}{B}: Attach Cranial Plating to target creature you control.
Equip {1}

Succumb to Temptation

Unholy Indenture

Enchant creature
When enchanted creature dies, return that card to the battlefield under your control with a +1/+1 counter on it.

Tragic Slip

Target creature gets -1/-1 until end of turn.
Morbid — That creature gets -13/-13 until end of turn instead if a creature died this turn.

Whispersilk Cloak

Equipped creature can't be blocked and has shroud. (It can't be the target of spells or abilities.)
Equip {2}

Murder

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.)

Catacomb Crocodile

Doom Blade

Golem-Skin Gauntlets

Equipped creature gets +1/+0 for each Equipment attached to it.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery. This card enters unattached and stays on the battlefield if the creature leaves.)

Cliffhaven Kitesail

When Cliffhaven Kitesail enters, attach it to target creature you control.
Equipped creature has flying.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Armory of Iroas

Whenever equipped creature attacks, put a +1/+1 counter on it.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Clutch of Undeath

Enchant creature
Enchanted creature gets +3/+3 as long as it's a Zombie. Otherwise, it gets -3/-3.

Bogstomper

Charcoal Diamond

Charcoal Diamond enters tapped.
{T}: Add {B}.

Phyresis

Enchant creature
Enchanted creature has infect. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Gutter Skulk

Geth's Verdict

Target player sacrifices a creature of their choice and loses 1 life.

Contaminated Ground

Enchant land
Enchanted land is a Swamp.
Whenever enchanted land becomes tapped, its controller loses 2 life.

Infernal Idol

{T}: Add {B}.
{1}{B}{B}, {T}, Sacrifice Infernal Idol: You draw two cards and you lose 2 life.

Bojuka Bog

Bojuka Bog enters tapped.
When Bojuka Bog enters, exile target player's graveyard.
{T}: Add {B}.

Witch's Familiar

Rotting Fensnake

Resourceful Return

Return target creature card from your graveyard to your hand. If you control an artifact, draw a card.

Dross Crocodile

Rite of Consumption

As an additional cost to cast this spell, sacrifice a creature.
Rite of Consumption deals damage equal to the sacrificed creature's power to target player or planeswalker. You gain life equal to the damage dealt this way.

Reckoner's Bargain

As an additional cost to cast this spell, sacrifice an artifact or creature.
You gain life equal to the sacrificed permanent's mana value. Draw two cards.

Foreboding Fruit

Target player draws two cards and loses 2 life.
Adamant — If at least three black mana was spent to cast this spell, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")

Dredging Claw

Equipped creature gets +1/+0 and has menace. (It can't be blocked except by two or more creatures.)
Whenever a creature enters from your graveyard, you may attach Dredging Claw to it.
Equip {1}{B} ({1}{B}: Attach to target creature you control. Equip only as a sorcery.)

Sign in Blood

Target player draws two cards and loses 2 life.

Leaden Myr

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Dark Ritual

Soldevi Adnate

{T}, Sacrifice a black or artifact creature: Add an amount of {B} equal to the sacrificed creature's mana value.

Toxic Stench

Target nonblack creature gets -1/-1 until end of turn.
Threshold — If seven or more cards are in your graveyard, instead destroy that creature. It can't be regenerated.

Haunted Cloak

Equipped creature has vigilance, trample, and haste.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Cast Down

Witch's Cottage

({T}: Add {B}.)
Witch's Cottage enters tapped unless you control three or more other Swamps.
When Witch's Cottage enters untapped, you may put target creature card from your graveyard on top of your library.