Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters the battlefield, 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.)

Barren Moor

Barren Moor enters the battlefield tapped.
{T}: Add {B}.
Cycling {B} ({B}, Discard this card: Draw a card.)

Wrench Mind

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

Choking Sands

Destroy target non-Swamp land. If that land was nonbasic, Choking Sands deals 2 damage to the land's controller.

Death Watch

Enchant creature
When enchanted creature dies, its controller loses life equal to its power and you gain life equal to its toughness.

Tendrils of Corruption

Tendrils of Corruption deals X damage to target creature and you gain X life, where X is the number of Swamps you control.

Chainer's Edict

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

Oubliette

When Oubliette enters the battlefield, 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.)

Duress

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

Crypt Rats

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

Chittering Rats

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

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.

Thorn of the Black Rose

Deathtouch
When Thorn of the Black Rose enters the battlefield, you become the monarch.

Bojuka Bog

Bojuka Bog enters the battlefield tapped.
When Bojuka Bog enters the battlefield, exile target player's graveyard.
{T}: Add {B}.

Defile

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

Phyrexian Rager

When Phyrexian Rager enters the battlefield, you draw a card and you lose 1 life.

Cuombajj Witches

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

Distress

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

Swamp

Echoing Decay

Target creature and all other creatures with the same name as that creature get -2/-2 until end of turn.