Plaguebearer

{X}{X}{B}: Destroy target nonblack creature with mana value X.

Infernal Contract

Draw four cards. You lose half your life, rounded up.

Snuff Out

If you control a Swamp, you may pay 4 life rather than pay this spell's mana cost.
Destroy target nonblack creature. It can't be regenerated.

Bubbling Muck

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

Keeper of the Dead

{B}, {T}: Choose target opponent who has at least two fewer creature cards in their graveyard than you do as you activate this ability. Destroy target nonblack creature that player controls.

Vebulid

Vebulid enters with a +1/+1 counter on it.
At the beginning of your upkeep, you may put a +1/+1 counter on Vebulid.
When Vebulid attacks or blocks, destroy it at end of combat.

Nantuko Shade

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

Maggot Carrier

When Maggot Carrier enters, each player loses 1 life.

Sanguine Guard

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

Duskwalker

Kicker {3}{B} (You may pay an additional {3}{B} as you cast this spell.)
If Duskwalker was kicked, it enters with two +1/+1 counters on it and with fear. (It can't be blocked except by artifact creatures and/or black creatures.)

Skittering Skirge

Flying
When you cast a creature spell, sacrifice Skittering Skirge.

Corpse Harvester

{1}{B}, {T}, Sacrifice a creature: Search your library for a Zombie card and a Swamp card, reveal them, put them into your hand, then shuffle.

Crypt Sliver

All Slivers have "{T}: Regenerate target Sliver."

Unworthy Dead

Headhunter

Whenever Headhunter deals combat damage to a player, that player discards a card.
Morph {B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Wall of Spears

Defender (This creature can't attack.)
First strike

Festering Goblin

When Festering Goblin dies, target creature gets -1/-1 until end of turn.

Ravenous Rats

When Ravenous Rats enters, target opponent discards a card.

Blood Pet

Phyrexian Arena

At the beginning of your upkeep, you draw a card and you lose 1 life.

Urborg Skeleton

Kicker {3} (You may pay an additional {3} as you cast this spell.)
{B}: Regenerate Urborg Skeleton.
If Urborg Skeleton was kicked, it enters with a +1/+1 counter on it.

Necrologia

Cast this spell only during your end step.
As an additional cost to cast this spell, pay X life.
Draw X cards.

Skulltap

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Entrails Feaster

At the beginning of your upkeep, you may exile a creature card from a graveyard. If you do, put a +1/+1 counter on Entrails Feaster. If you don't, tap Entrails Feaster.

Plague Spitter

At the beginning of your upkeep, Plague Spitter deals 1 damage to each creature and each player.
When Plague Spitter dies, it deals 1 damage to each creature and each player.

Nightmare

Flying (This creature can't be blocked except by creatures with flying or reach.)
Nightmare's power and toughness are each equal to the number of Swamps you control.

Misshapen Fiend

Hecatomb

When Hecatomb enters, sacrifice Hecatomb unless you sacrifice four creatures.
Tap an untapped Swamp you control: Hecatomb deals 1 damage to any target.

Ornithopter

Sengir Autocrat

When Sengir Autocrat enters, create three 0/1 black Serf creature tokens.
When Sengir Autocrat leaves the battlefield, exile all Serf tokens.

Fog of Gnats

Mind Sludge

Target player discards a card for each Swamp you control.

Mutilate

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

Carrion Feeder

Carrion Feeder can't block.
Sacrifice a creature: Put a +1/+1 counter on Carrion Feeder.

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.