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.)

Cliffhaven Vampire

Flying
Whenever you gain life, each opponent loses 1 life.

Scoured Barrens

Scoured Barrens enters tapped.
When Scoured Barrens enters, you gain 1 life.
{T}: Add {W} or {B}.

Soul Warden

Whenever another creature enters, you gain 1 life.

Shattered Angel

Flying
Whenever a land an opponent controls enters, you may gain 3 life.

Divinity of Pride

Flying, lifelink
Divinity of Pride gets +4/+4 as long as you have 25 or more life.

Caves of Koilos

{T}: Add {C}.
{T}: Add {W} or {B}. Caves of Koilos deals 1 damage to you.

Anguished Unmaking

Exile target nonland permanent. You lose 3 life.

Ayli, Eternal Pilgrim

Deathtouch
{1}, Sacrifice another creature: You gain life equal to the sacrificed creature's toughness.
{1}{W}{B}, Sacrifice another creature: Exile target nonland permanent. Activate only if you have at least 10 life more than your starting life total.

Obzedat, Ghost Council

When Obzedat, Ghost Council enters, target opponent loses 2 life and you gain 2 life.
At the beginning of your end step, you may exile Obzedat. If you do, return it to the battlefield under its owner's control at the beginning of your next upkeep. It gains haste.

Vizkopa Guildmage

{1}{W}{B}: Target creature gains lifelink until end of turn.
{1}{W}{B}: Whenever you gain life this turn, each opponent loses that much life.

Ajani's Pridemate

Whenever you gain life, put a +1/+1 counter on Ajani's Pridemate.

Sorin, Vengeful Bloodlord

During your turn, creatures and planeswalkers you control have lifelink.
+2: Sorin, Vengeful Bloodlord deals 1 damage to target player or planeswalker.
−X: Return target creature card with mana value X from your graveyard to the battlefield. That creature is a Vampire in addition to its other types.

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Sun Droplet

Whenever you're dealt damage, put that many charge counters on Sun Droplet.
At the beginning of each upkeep, you may remove a charge counter from Sun Droplet. If you do, you gain 1 life.

Blood Artist

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

Hero's Downfall

Ajani, Strength of the Pride

+1: You gain life equal to the number of creatures you control plus the number of planeswalkers you control.
−2: Create a 2/2 white Cat Soldier creature token named Ajani's Pridemate with "Whenever you gain life, put a +1/+1 counter on Ajani's Pridemate."
0: If you have at least 15 life more than your starting life total, exile Ajani, Strength of the Pride and each artifact and creature your opponents control.

Mother of Runes

{T}: Target creature you control gains protection from the color of your choice until end of turn.

Elenda, the Dusk Rose

Lifelink
Whenever another creature dies, put a +1/+1 counter on Elenda, the Dusk Rose.
When Elenda dies, create X 1/1 white Vampire creature tokens with lifelink, where X is Elenda's power.

Felidar Sovereign

Vigilance, lifelink
At the beginning of your upkeep, if you have 40 or more life, you win the game.

Serra Avatar

Serra Avatar's power and toughness are each equal to your life total.
When Serra Avatar is put into a graveyard from anywhere, shuffle it into its owner's library.

Krav, the Unredeemed

Partner with Regna, the Redeemer (When this creature enters, target player may put Regna into their hand from their library, then shuffle.)
{B}, Sacrifice X creatures: Target player draws X cards and gains X life. Put X +1/+1 counters on Krav, the Unredeemed.

Utter End

Radiant Fountain

When Radiant Fountain enters, you gain 2 life.
{T}: Add {C}.

Temple of Aclazotz

(Transforms from Arguel's Blood Fast.)
{T}: Add {B}.
{T}, Sacrifice a creature: You gain life equal to the sacrificed creature's toughness.

Arguel's Blood Fast

{1}{B}, Pay 2 life: Draw a card.
At the beginning of your upkeep, if you have 5 or less life, you may transform Arguel's Blood Fast.

Arguel's Blood Fast // Temple of Aclazotz

Drana's Emissary

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

Crested Sunmare

Other Horses you control have indestructible.
At the beginning of each end step, if you gained life this turn, create a 5/5 white Horse creature token.

Sunscorch Regent

Flying
Whenever an opponent casts a spell, put a +1/+1 counter on Sunscorch Regent and you gain 1 life.

Aetherflux Reservoir

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

Ormendahl, Profane Prince

Westvale Abbey

{T}: Add {C}.
{5}, {T}, Pay 1 life: Create a 1/1 white and black Human Cleric creature token.
{5}, {T}, Sacrifice five creatures: Transform Westvale Abbey, then untap it.

Westvale Abbey // Ormendahl, Profane Prince

Sanguine Bond

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

Regal Bloodlord

Flying
At the beginning of each end step, if you gained life this turn, create a 1/1 black Bat creature token with flying.

Wall of Reverence

Defender, flying
At the beginning of your end step, you may gain life equal to the power of target creature you control.

Death Grasp

Death Grasp deals X damage to any target. You gain X life.

Merciless Eviction

Choose one —
• Exile all artifacts.
• Exile all creatures.
• Exile all enchantments.
• Exile all planeswalkers.

Kambal, Consul of Allocation

Whenever an opponent casts a noncreature spell, that player loses 2 life and you gain 2 life.

Glimmerpost

When Glimmerpost enters, you gain 1 life for each Locus on the battlefield.
{T}: Add {C}.

Authority of the Consuls

Creatures your opponents control enter tapped.
Whenever a creature an opponent controls enters, you gain 1 life.

Righteous Cause

Whenever a creature attacks, you gain 1 life.

Vault of the Archangel

{T}: Add {C}.
{2}{W}{B}, {T}: Creatures you control gain deathtouch and lifelink until end of turn.

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.

Karlov of the Ghost Council

Whenever you gain life, put two +1/+1 counters on Karlov of the Ghost Council.
{W}{B}, Remove six +1/+1 counters from Karlov of the Ghost Council: Exile target creature.

Deathgreeter

Whenever another creature dies, you may gain 1 life.

Isolated Chapel

Isolated Chapel enters tapped unless you control a Plains or a Swamp.
{T}: Add {W} or {B}.

Snow-Covered Swamp

Bloodthirsty Aerialist

Flying
Whenever you gain life, put a +1/+1 counter on Bloodthirsty Aerialist.

Ajani's Welcome

Whenever a creature you control enters, you gain 1 life.

Nyx-Fleece Ram

At the beginning of your upkeep, you gain 1 life.

Kaya's Guile

Choose two —
• Each opponent sacrifices a creature.
• Exile all opponents' graveyards.
• Create a 1/1 white and black Spirit creature token with flying.
• You gain 4 life.
Entwine {3} (Choose all if you pay the entwine cost.)

Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Whip of Erebos

Creatures you control have lifelink.
{2}{B}{B}, {T}: Return target creature card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step. If it would leave the battlefield, exile it instead of putting it anywhere else. Activate only as a sorcery.

Sunbond

Enchant creature
Enchanted creature has "Whenever you gain life, put that many +1/+1 counters on this creature."

Angel of Vitality

Flying
If you would gain life, you gain that much life plus 1 instead.
Angel of Vitality gets +2/+2 as long as you have 25 or more life.

Shambling Vent

Shambling Vent enters tapped.
{T}: Add {W} or {B}.
{1}{W}{B}: Shambling Vent becomes a 2/3 white and black Elemental creature with lifelink until end of turn. It's still a land.

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.

Fumigate

Destroy all creatures. You gain 1 life for each creature destroyed this way.

Pristine Talisman

Vona, Butcher of Magan

Vigilance, lifelink
{T}, Pay 7 life: Destroy target nonland permanent. Activate only during your turn.

Seraph Sanctuary

When Seraph Sanctuary enters, you gain 1 life.
Whenever an Angel you control enters, you gain 1 life.
{T}: Add {C}.

Ashes of the Abhorrent

Players can't cast spells from graveyards or activate abilities of cards in graveyards.
Whenever a creature dies, you gain 1 life.

Tablet of the Guilds

As Tablet of the Guilds enters, choose two colors.
Whenever you cast a spell, if it's at least one of the chosen colors, you gain 1 life for each of the chosen colors it is.

Talisman of Hierarchy

{T}: Add {C}.
{T}: Add {W} or {B}. Talisman of Hierarchy deals 1 damage to you.

Kabira Crossroads

Kabira Crossroads enters tapped.
When Kabira Crossroads enters, you gain 2 life.
{T}: Add {W}.

Snow-Covered Plains

Tainted Field

{T}: Add {C}.
{T}: Add {W} or {B}. Activate only if you control a Swamp.

Orzhov Signet

Impassioned Orator

Whenever another creature you control enters, you gain 1 life.

Blind Obedience

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.)
Artifacts and creatures your opponents control enter tapped.

Sol Ring

Debt to the Deathless

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

Sun Titan

Vigilance
Whenever Sun Titan enters or attacks, you may return target permanent card with mana value 3 or less from your graveyard to the battlefield.

Epicure of Blood

Whenever you gain life, each opponent loses 1 life.

Command Tower

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

Chalice of Death

Chalice of Life

{T}: You gain 1 life. Then if you have at least 10 life more than your starting life total, transform Chalice of Life.

Chalice of Life // Chalice of Death

Regna, the Redeemer

Partner with Krav, the Unredeemed (When this creature enters, target player may put Krav into their hand from their library, then shuffle.)
Flying
At the beginning of each end step, if your team gained life this turn, create two 1/1 white Warrior creature tokens.

Suture Priest

Whenever another creature you control enters, you may gain 1 life.
Whenever a creature an opponent controls enters, you may have that player lose 1 life.