Quag Sickness

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

Witherbloom Campus

Witherbloom Campus enters the battlefield tapped.
{T}: Add {B} or {G}.
{4}, {T}: Scry 1.

Gravetiller Wurm

Trample
Morbid — Gravetiller Wurm enters the battlefield with four +1/+1 counters on it if a creature died this turn.

Ulvenwald Bear

Morbid — When Ulvenwald Bear enters the battlefield, if a creature died this turn, put two +1/+1 counters on target creature.

Instill Infection

Put a -1/-1 counter on target creature.
Draw a card.

Core Prowler

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
When Core Prowler dies, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Reaper of Sheoldred

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Whenever a source deals damage to Reaper of Sheoldred, that source's controller gets a poison counter.

Necroskitter

Wither (This deals damage to creatures in the form of -1/-1 counters.)
Whenever a creature an opponent controls with a -1/-1 counter on it dies, you may return that card to the battlefield under your control.

Magewright's Stone

{1}, {T}: Untap target creature that has an activated ability with {T} in its cost.

Vhati il-Dal

{T}: Until end of turn, target creature has base power 1 or base toughness 1.

Enfeeblement

Enchant creature (Target a creature as you cast this. This card enters the battlefield attached to that creature.)
Enchanted creature gets -2/-2.

Reaper from the Abyss

Flying
Morbid — At the beginning of each end step, if a creature died this turn, destroy target non-Demon creature.

Forest

Whispering Specter

Flying
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Whenever Whispering Specter deals combat damage to a player, you may sacrifice it. If you do, that player discards a card for each poison counter they have.

Plaguemaw Beast

{T}, Sacrifice a creature: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

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.

Stabbing Pain

Target creature gets -1/-1 until end of turn. Tap that creature.

Eyeblight Assassin

When Eyeblight Assassin enters the battlefield, target creature an opponent controls gets -1/-1 until end of turn.

Instill Energy

Enchant creature
Enchanted creature can attack as though it had haste.
{0}: Untap enchanted creature. Activate only during your turn and only once each turn.

Tangle Angler

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
{G}: Target creature blocks Tangle Angler this turn if able.

Extinguish All Hope

Smell Fear

Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Target creature you control fights up to one target creature you don't control.

Virulent Wound

Put a -1/-1 counter on target creature. When that creature dies this turn, its controller gets a poison counter.

Jungle Hollow

Jungle Hollow enters the battlefield tapped.
When Jungle Hollow enters the battlefield, you gain 1 life.
{T}: Add {B} or {G}.

Corpse Cur

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
When Corpse Cur enters the battlefield, you may return target creature card with infect from your graveyard to your hand.

Necropede

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
When Necropede dies, you may put a -1/-1 counter on target creature.

Golgari Guildgate

Golgari Guildgate enters the battlefield tapped.
{T}: Add {B} or {G}.

Weakness

Enchant creature
Enchanted creature gets -2/-1.

Skulduggery

Until end of turn, target creature you control gets +1/+1 and target creature an opponent controls gets -1/-1.

Weathered Runestone

Nonland permanent cards in graveyards and libraries can't enter the battlefield.
Players can't cast spells from graveyards or libraries.

Carnifex Demon

Flying
Carnifex Demon enters the battlefield with two -1/-1 counters on it.
{B}, Remove a -1/-1 counter from Carnifex Demon: Put a -1/-1 counter on each other creature.

Screams from Within

Enchant creature
Enchanted creature gets -1/-1.
When enchanted creature dies, return Screams from Within from your graveyard to the battlefield.

Spread the Sickness

Destroy target creature, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Deathreap Ritual

Morbid — At the beginning of each end step, if a creature died this turn, you may draw a card.

Weigh Down

As an additional cost to cast this spell, exile a creature card from your graveyard.
Target creature gets -3/-3 until end of turn.

Malicious Affliction

Morbid — When you cast this spell, if a creature died this turn, you may copy Malicious Affliction and may choose a new target for the copy.
Destroy target nonblack creature.

Dark Ritual

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.)

Worst Fears

You control target player during that player's next turn. Exile Worst Fears. (You see all cards that player could see and make all decisions for the player.)

Seeker of Skybreak

Foul Orchard

Foul Orchard enters the battlefield tapped.
{T}: Add {B} or {G}.

Defile

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

Swamp

Hunger of the Howlpack

Put a +1/+1 counter on target creature.
Morbid — Put three +1/+1 counters on that creature instead if a creature died this turn.

Septic Rats

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Whenever Septic Rats attacks, if defending player is poisoned, it gets +1/+1 until end of turn.

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.

Dead Weight

Enchant creature
Enchanted creature gets -2/-2.

Harvester of Souls

Deathtouch
Whenever another nontoken creature dies, you may draw a card.

Kaervek, the Spiteful

Umezawa's Charm

Choose one —
• Target creature gets +2/+2 until end of turn.
• Target creature gets -1/-1 until end of turn.
• You gain 2 life.

Skemfar Elderhall

Skemfar Elderhall enters the battlefield tapped.
{T}: Add {G}.
{2}{B}{B}{G}, {T}, Sacrifice Skemfar Elderhall: Up to one target creature you don't control gets -2/-2 until end of turn. Create two 1/1 green Elf Warrior creature tokens. Activate only as a sorcery.

Viridian Longbow

Equipped creature has "{T}: This creature deals 1 damage to any target."
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery. This card enters the battlefield unattached and stays on the battlefield if the creature leaves.)

Rot Wolf

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Whenever a creature dealt damage by Rot Wolf this turn dies, you may draw a card.

Drown in Sorrow

All creatures get -2/-2 until end of turn. Scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)

Death Wind

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

Festerhide Boar

Trample
Morbid — Festerhide Boar enters the battlefield with two +1/+1 counters on it if a creature died this turn.

Gruesome Deformity

Enchant creature
Enchanted creature has intimidate. (It can't be blocked except by artifact creatures and/or creatures that share a color with it.)

Grafted Exoskeleton

Equipped creature gets +2/+2 and has infect. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Whenever Grafted Exoskeleton becomes unattached from a permanent, sacrifice that permanent.
Equip {2}

Phyrexian Vatmother

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
At the beginning of your upkeep, you get a poison counter.

Caravan Vigil

Search your library for a basic land card, reveal it, put it into your hand, then shuffle.
Morbid — You may put that card onto the battlefield instead of putting it into your hand if a creature died this turn.

Midnight Banshee

Wither (This deals damage to creatures in the form of -1/-1 counters.)
At the beginning of your upkeep, put a -1/-1 counter on each nonblack creature.

Wring Flesh

Target creature gets -3/-1 until end of turn.

Puppet Strings

{2}, {T}: You may tap or untap target creature.

Fourth Bridge Prowler

When Fourth Bridge Prowler enters the battlefield, you may have target creature get -1/-1 until end of turn.

Skeleton Archer

When Skeleton Archer enters the battlefield, it deals 1 damage to any target.

Black Sun's Zenith

Put X -1/-1 counters on each creature. Shuffle Black Sun's Zenith into its owner's library.

Staff of Nin

At the beginning of your upkeep, draw a card.
{T}: Staff of Nin deals 1 damage to any target.

Golgari Rot Farm

Golgari Rot Farm enters the battlefield tapped.
When Golgari Rot Farm enters the battlefield, return a land you control to its owner's hand.
{T}: Add {B}{G}.

Hornet Sting

Hornet Sting deals 1 damage to any target.

Night of Souls' Betrayal

Tree of Perdition

Defender
{T}: Exchange target opponent's life total with Tree of Perdition's toughness.

Hapatra, Vizier of Poisons

Whenever Hapatra, Vizier of Poisons deals combat damage to a player, you may put a -1/-1 counter on target creature.
Whenever you put one or more -1/-1 counters on a creature, create a 1/1 green Snake creature token with deathtouch.

Morkrut Banshee

Morbid — When Morkrut Banshee enters the battlefield, if a creature died this turn, target creature gets -4/-4 until end of turn.

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.)

Somberwald Spider

Reach (This creature can block creatures with flying.)
Morbid — Somberwald Spider enters the battlefield with two +1/+1 counters on it if a creature died this turn.

Cystbearer

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Throne of Geth

{T}, Sacrifice an artifact: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)