Agent of the Shadow Thieves

Commander creatures you own have "Whenever this creature attacks a player, if no opponent has more life than that player, put a +1/+1 counter on this creature. It gains deathtouch and indestructible until end of turn."

Have

Stinging Study

You draw X cards and you lose X life, where X is the mana value of a commander you own on the battlefield or in the command zone.

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.

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.

Sangromancer

Flying
Whenever a creature an opponent controls dies, you may gain 3 life.
Whenever an opponent discards a card, you may gain 3 life.

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.

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Savor

Target creature gets -2/-2 until end of turn. Create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")

Demon's Horn

Whenever a player casts a black spell, you may gain 1 life.

Font of Agonies

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

Decree of Pain

Destroy all creatures. They can't be regenerated. Draw a card for each creature destroyed this way.
Cycling {3}{B}{B} ({3}{B}{B}, Discard this card: Draw a card.)
When you cycle this card, all creatures get -2/-2 until end of turn.

Noxious Gearhulk

Menace
When this creature enters, you may destroy another target creature. If a creature is destroyed this way, you gain life equal to its toughness.

Alhammarret's Archive

If you would gain life, you gain twice that much life instead.
If you would draw a card except the first one you draw in each of your draw steps, draw two cards instead.

Cut of the Profits

Casualty 3 (As you cast this spell, you may sacrifice a creature with power 3 or greater. When you do, copy this spell.)
You draw X cards and you lose X life.

Plaguecrafter

When this creature enters, each player sacrifices a creature or planeswalker of their choice. Each player who can't discards a card.

Shard of the Nightbringer

Flying
Drain Life — When this creature enters, if you cast it, target opponent loses half their life, rounded up. You gain life equal to the life lost this way.

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.

Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.

Elixir of Immortality

{2}, {T}: You gain 5 life. Shuffle this artifact and your graveyard into their owner's library.

Vampire Nighthawk

Flying
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Feast on the Fallen

At the beginning of each upkeep, if an opponent lost life last turn, put a +1/+1 counter on target creature you control.

Professor's Warning

Choose one —
• Put a +1/+1 counter on target creature.
• Target creature gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

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.)

Creeping Bloodsucker

At the beginning of your upkeep, this creature deals 1 damage to each opponent. You gain life equal to the damage dealt this way.

Radiant Fountain

When this land enters, you gain 2 life.
{T}: Add {C}.

K'rrik, Son of Yawgmoth

({B/P} can be paid with either {B} or 2 life.)
Lifelink
For each {B} in a cost, you may pay 2 life rather than pay that mana.
Whenever you cast a black spell, put a +1/+1 counter on K'rrik.

Exquisite Blood

Whenever an opponent loses life, you gain that much life.

Prism Ring

As this artifact enters, choose a color.
Whenever you cast a spell of the chosen color, you gain 1 life.

Arcane Signet

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

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice this artifact: Draw a card.

Charcoal Diamond

This artifact enters tapped.
{T}: Add {B}.

Blood Artist

Whenever this creature or another creature dies, target player loses 1 life and you gain 1 life.

Cosmos Elixir

At the beginning of your end step, draw a card if your life total is greater than your starting life total. Otherwise, you gain 2 life.

Read the Bones

Scry 2, then draw two cards. You lose 2 life. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Staff of the Death Magus

Whenever you cast a black spell or a Swamp you control enters, you gain 1 life.

Accursed Marauder

When this creature enters, each player sacrifices a nontoken creature of their choice.

Dregs of Sorrow

Destroy X target nonblack creatures. Draw X cards.

Greed

Exsanguinate

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

Their Number Is Legion

Create X tapped 2/2 black Necron Warrior artifact creature tokens, then you gain life equal to the number of artifacts you control. Exile Their Number Is Legion.
You may cast this card from your graveyard.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Bubbling Muck

Until end of turn, whenever a player taps a Swamp for mana, that player adds an additional {B}.

Damnable Pact

Target player draws X cards and loses X life.

New Blood

As an additional cost to cast this spell, tap an untapped Vampire you control.
Gain control of target creature. Change the text of that creature by replacing all instances of one creature type with Vampire.

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.

Falkenrath Noble

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

Battle at the Bridge

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Target creature gets -X/-X until end of turn. You gain X life.

Murder

Stargaze

Look at twice X cards from the top of your library. Put X cards from among them into your hand and the rest into your graveyard. You lose X life.

Paradise Plume

As this artifact enters, choose a color.
Whenever a player casts a spell of the chosen color, you may gain 1 life.
{T}: Add one mana of the chosen color.

Aetherflux Reservoir

Whenever you cast a spell, you gain 1 life for each spell you've cast this turn.
Pay 50 life: This artifact deals 50 damage to any target.

Sol Ring

Infernal Grasp

Destroy target creature. You lose 2 life.

Pontiff of Blight

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.)
Other creatures you control have extort. (If a creature has multiple instances of extort, each triggers separately.)

Syphon Mind

Each other player discards a card. You draw a card for each card discarded this way.

Sanguine Bond

Whenever you gain life, target opponent loses that much life.

Pristine Talisman

Profane Command

Choose two —
• Target player loses X life.
• Return target creature card with mana value X or less from your graveyard to the battlefield.
• Target creature gets -X/-X until end of turn.
• Up to X target creatures gain fear until end of turn. (They can't be blocked except by artifact creatures and/or black creatures.)

Dogged Pursuit

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

Bloodletter of Aclazotz

Flying
If an opponent would lose life during your turn, they lose twice that much life instead. (Damage causes loss of life.)

Well of Lost Dreams

Whenever you gain life, you may pay {X}, where X is less than or equal to the amount of life you gained. If you do, draw X cards.

Sign in Blood

Target player draws two cards and loses 2 life.

Bontu's Monument

Black creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, each opponent loses 1 life and you gain 1 life.