Nyxathid

As Nyxathid enters, choose an opponent.
Nyxathid gets -1/-1 for each card in the chosen player's hand.

Gatekeeper of Malakir

Kicker {B} (You may pay an additional {B} as you cast this spell.)
When Gatekeeper of Malakir enters, if it was kicked, target player sacrifices a creature.

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.

Ravenous Chupacabra

When Ravenous Chupacabra enters, destroy target creature an opponent controls.

Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Lisette, Dean of the Root

Whenever you gain life, you may pay {1}. If you do, put a +1/+1 counter on each creature you control and those creatures gain trample until end of turn.

Valentin, Dean of the Vein

Menace, lifelink
If a nontoken creature an opponent controls would die, exile it instead. When you do, you may pay {2}. If you do, create a 1/1 black and green Pest creature token with "When this creature dies, you gain 1 life."

Valentin, Dean of the Vein // Lisette, Dean of the Root

Grimdancer

Grimdancer enters with your choice of two different counters on it from among menace, deathtouch, and lifelink.

Inquisition of Kozilek

Target player reveals their hand. You choose a nonland card from it with mana value 3 or less. That player discards that card.

Abhorrent Overlord

Flying
When Abhorrent Overlord enters, create a number of 1/1 black Harpy creature tokens with flying equal to your devotion to black. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)
At the beginning of your upkeep, sacrifice a creature.

Chittering Rats

When Chittering Rats enters, target opponent puts a card from their hand on top of their library.

Nullpriest of Oblivion

Kicker {3}{B}
Menace, lifelink
When Nullpriest of Oblivion enters, if it was kicked, return target creature card from your graveyard to the battlefield.

Swamp

Marshmist Titan

This spell costs {X} less to cast, where X is your devotion to black. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Vampire Nighthawk

Duress

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

Nantuko Shade

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

Vampire Cutthroat

Skulk (This creature can't be blocked by creatures with greater power.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Hymn to Tourach

Target player discards two cards at random.

Sign in Blood

Target player draws two cards and loses 2 life.

Nighthawk Scavenger

Flying, deathtouch, lifelink
Nighthawk Scavenger's power is equal to 1 plus the number of card types among cards in your opponents' graveyards.

Shrieking Affliction

At the beginning of each opponent's upkeep, if that player has one or fewer cards in hand, they lose 3 life.

Gifted Aetherborn

Defile

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

Dread Shade

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

Underworld Hermit

When Underworld Hermit enters, create a number of 1/1 green Squirrel creature tokens equal to your devotion to black. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)