Have

Gray Merchant of Asphodel

When this creature 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.)

Witch's Cottage

({T}: Add {B}.)
This land enters tapped unless you control three or more other Swamps.
When this land enters untapped, you may put target creature card from your graveyard on top of your library.

Geth's Verdict

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

Nihil Spellbomb

{T}, Sacrifice this artifact: Exile target player's graveyard.
When this artifact is put into a graveyard from the battlefield, you may pay {B}. If you do, draw a card.

Crypt Rats

{X}: This creature deals X damage to each creature and each player. Spend only black mana on X.

Consuming Sepulcher

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

Tithing Blade

When this artifact enters, each opponent sacrifices a creature of their choice.
Craft with creature {4}{B} ({4}{B}, Exile this artifact, Exile a creature you control or a creature card from your graveyard: Return this card transformed under its owner's control. Craft only as a sorcery.)

Tithing Blade // Consuming Sepulcher

Bojuka Bog

This land enters tapped.
When this land enters, exile target player's graveyard.
{T}: Add {B}.

Swamp

Defile

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

Suffocating Fumes

Creatures your opponents control get -1/-1 until end of turn.
Cycling {2} ({2}, Discard this card: Draw a card.)

Cuombajj Witches

{T}: This creature deals 1 damage to any target and 1 damage to any target of an opponent's choice.

Chittering Rats

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

Cast Down

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.

Relic of Progenitus

{T}: Target player exiles a card from their graveyard.
{1}, Exile this artifact: Exile all graveyards. Draw a card.

Thorn of the Black Rose

Deathtouch
When this creature enters, you become the monarch.

Contaminated Ground

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

Unexpected Fangs

Put a +1/+1 counter and a lifelink counter on target creature.

Wrench Mind

Target player discards two cards unless they discard an artifact card.

Chainer's Edict

Target player sacrifices a creature of their choice.
Flashback {5}{B}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Troll of Khazad-dûm

This creature can't be blocked except by three or more creatures.
Swampcycling {1} ({1}, Discard this card: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.)

Deadly Dispute

As an additional cost to cast this spell, sacrifice an artifact or creature.
Draw two cards and create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Sign in Blood

Target player draws two cards and loses 2 life.

Duress

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