Have

Thrull Parasite

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.)
{T}, Pay 2 life: Remove a counter from target nonland permanent.

Dread Presence

Whenever a Swamp you control enters, choose one —
• You draw a card and you lose 1 life.
• Dread Presence deals 2 damage to any target and you gain 2 life.

Butcher of Malakir

Flying
Whenever Butcher of Malakir or another creature you control dies, each opponent sacrifices a creature of their choice.

Blight Mound

Attacking Pests you control get +1/+0 and have menace.
Whenever a nontoken creature you control dies, create a 1/1 black and green Pest creature token with "When this creature dies, you gain 1 life."

Crypt Rats

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

Torment of Hailfire

Repeat the following process X times. Each opponent loses 3 life unless that player sacrifices a nonland permanent of their choice or discards a card.

Zulaport Cutthroat

Whenever Zulaport Cutthroat or another creature you control dies, each opponent loses 1 life and you gain 1 life.

Nightmare Incursion

Search target player's library for up to X cards, where X is the number of Swamps you control, and exile them. Then that player shuffles.

Defile

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

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Sol Ring

Exsanguinate

Each opponent loses X life. You gain life equal to the life lost this way.

Leechridden Swamp

({T}: Add {B}.)
Leechridden Swamp enters tapped.
{B}, {T}: Each opponent loses 1 life. Activate only if you control two or more black permanents.

Urborg, Tomb of Yawgmoth

Each land is a Swamp in addition to its other land types.

Terramorphic Expanse

{T}, Sacrifice Terramorphic Expanse: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Grave Pact

Whenever a creature you control dies, each other player sacrifices a creature of their choice.

Ashnod's Altar

Erebos's Intervention

Choose one —
• Target creature gets -X/-X until end of turn. You gain X life.
• Exile up to twice X target cards from graveyards.

Font of Agonies

Whenever you pay life, put that many blood counters on Font of Agonies.
{1}{B}, Remove four blood counters from Font of Agonies: Destroy target creature.

Palace Siege

As Palace Siege enters, choose Khans or Dragons.
• Khans — At the beginning of your upkeep, return target creature card from your graveyard to your hand.
• Dragons — At the beginning of your upkeep, each opponent loses 2 life and you gain 2 life.

Evolving Wilds

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Ayara, First of Locthwain

Whenever Ayara, First of Locthwain or another black creature you control enters, each opponent loses 1 life and you gain 1 life.
{T}, Sacrifice another black creature: Draw a card.

Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.

Swamp

Vito, Thorn of the Dusk Rose

Whenever you gain life, target opponent loses that much life.
{3}{B}{B}: Creatures you control gain lifelink until end of turn.

Disciple of Bolas

When Disciple of Bolas enters, sacrifice another creature. You gain X life and draw X cards, where X is that creature's power.

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.)

Crypt Ghast

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.)
Whenever you tap a Swamp for mana, add an additional {B}.

Deathgreeter

Whenever another creature dies, you may gain 1 life.

Falkenrath Noble

Flying
Whenever Falkenrath Noble or another creature dies, target player loses 1 life and you gain 1 life.

Cabal Stronghold

{T}: Add {C}.
{3}, {T}: Add {B} for each basic Swamp you control.

Bolas's Citadel

You may look at the top card of your library any time.
You may play lands and cast spells from the top of your library. If you cast a spell this way, pay life equal to its mana value rather than pay its mana cost.
{T}, Sacrifice ten nonland permanents: Each opponent loses 10 life.