Syndicate Enforcer

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)

Withercrown

Enchant creature
Enchanted creature has base power 0 and has "At the beginning of your upkeep, you lose 1 life unless you sacrifice this creature."

Feebleness

Flash
Enchant creature
Enchanted creature gets -2/-1.

Ghoulflesh

Enchant creature
Enchanted creature gets -1/-1 and is a black Zombie in addition to its other colors and types.

Torture

Enchant creature
{1}{B}: Put a -1/-1 counter on enchanted creature.

Enfeeblement

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

Omen of the Dead

Flash
When Omen of the Dead enters, return target creature card from your graveyard to your hand.
{2}{B}, Sacrifice Omen of the Dead: Scry 2.

Chime of Night

Enchant creature
When Chime of Night is put into a graveyard from the battlefield, destroy target nonblack creature.

Merrow Bonegnawer

{T}: Target player exiles a card from their graveyard.
Whenever you cast a black spell, you may untap Merrow Bonegnawer.

Yoke of the Damned

Enchant creature
When a creature dies, destroy enchanted creature.

Crippling Blight

Enchant creature
Enchanted creature gets -1/-1 and can't block.

Basilica Screecher

Flying
Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)

Tortured Existence

{B}, Discard a creature card: Return target creature card from your graveyard to your hand.

Ill-Gotten Inheritance

At the beginning of your upkeep, Ill-Gotten Inheritance deals 1 damage to each opponent and you gain 1 life.
{5}{B}, Sacrifice Ill-Gotten Inheritance: It deals 4 damage to target opponent and you gain 4 life.

Blightcaster

Whenever you cast an enchantment spell, you may have target creature get -2/-2 until end of turn.

Quag Sickness

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

Mire's Grasp

Enchant creature
Enchanted creature gets -3/-3.

Melancholy

Enchant creature
When Melancholy enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.
At the beginning of your upkeep, sacrifice Melancholy unless you pay {B}.

Grave Peril

When a nonblack creature enters, sacrifice Grave Peril. If you do, destroy that creature.

Death's Approach

Enchant creature
Enchanted creature gets -X/-X, where X is the number of creature cards in its controller's graveyard.

Dogged Pursuit

At the beginning of your end step, each opponent loses 1 life and you gain 1 life.

Crown of Suspicion

Enchant creature
Enchanted creature gets +2/-1.
Sacrifice Crown of Suspicion: Enchanted creature and other creatures that share a creature type with it get +2/-1 until end of turn.

Dead Weight

Enchant creature
Enchanted creature gets -2/-2.

Seal of Doom

Sacrifice Seal of Doom: Destroy target nonblack creature. It can't be regenerated.

Eternal Thirst

Enchant creature
Enchanted creature has lifelink and "Whenever a creature an opponent controls dies, put a +1/+1 counter on this creature." (Damage dealt by a creature with lifelink also causes its controller to gain that much life.)

Grave Servitude

You may cast Grave Servitude as though it had flash. If you cast it any time a sorcery couldn't have been cast, the controller of the permanent it becomes sacrifices it at the beginning of the next cleanup step.
Enchant creature
Enchanted creature gets +3/-1 and is black.

Sicken

Enchant creature
Enchanted creature gets -1/-1.
Cycling {2} ({2}, Discard this card: Draw a card.)

Grim Guardian

Constellation — Whenever Grim Guardian or another enchantment you control enters, each opponent loses 1 life.

Oubliette

When Oubliette enters, target creature phases out until Oubliette leaves the battlefield. Tap that creature as it phases in this way. (Auras and Equipment phase out with it. While permanents are phased out, they're treated as though they don't exist.)

Stab Wound

Enchant creature
Enchanted creature gets -2/-2.
At the beginning of the upkeep of enchanted creature's controller, that player loses 2 life.

Cursed Flesh

Enchant creature
Enchanted creature gets -1/-1 and has fear. (It can't be blocked except by artifact creatures and/or black creatures.)

Weakness

Enchant creature
Enchanted creature gets -2/-1.

Cloak of Confusion

Enchant creature you control
Whenever enchanted creature attacks and isn't blocked, you may have it assign no combat damage this turn. If you do, defending player discards a card at random.

Paralyze

Enchant creature
When Paralyze enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.
At the beginning of the upkeep of enchanted creature's controller, that player may pay {4}. If the player does, untap the creature.

Dreadbringer Lampads

Constellation — Whenever Dreadbringer Lampads or another enchantment you control enters, target creature gains intimidate until end of turn. (It can't be blocked except by artifact creatures and/or creatures that share a color with it.)

Cartouche of Ambition

Enchant creature you control
When Cartouche of Ambition enters, you may put a -1/-1 counter on target creature.
Enchanted creature gets +1/+1 and has lifelink.

Grisly Transformation

Enchant creature
When Grisly Transformation enters, draw a card.
Enchanted creature has intimidate. (It can't be blocked except by artifact creatures and/or creatures that share a color with it.)

Boon of Emrakul

Enchant creature
Enchanted creature gets +3/-3.

Casting of Bones

Enchant creature
When enchanted creature dies, draw three cards, then discard one of them.

Viper's Kiss

Enchant creature
Enchanted creature gets -1/-1, and its activated abilities can't be activated.

Clinging Darkness

Enchant creature
Enchanted creature gets -4/-1.

Soul Stair Expedition

Landfall — Whenever a land you control enters, you may put a quest counter on Soul Stair Expedition.
Remove three quest counters from Soul Stair Expedition and sacrifice it: Return up to two target creature cards from your graveyard to your hand.

Ancestral Vengeance

Enchant creature
When Ancestral Vengeance enters, put a +1/+1 counter on target creature you control.
Enchanted creature gets -1/-1.

Pestilence

At the beginning of the end step, if no creatures are on the battlefield, sacrifice Pestilence.
{B}: Pestilence deals 1 damage to each creature and each player.