Have

Serra Ascendant

Lifelink (Damage dealt by this creature also causes you to gain that much life.)
As long as you have 30 or more life, Serra Ascendant gets +5/+5 and has flying.

Utter End

Nykthos Paragon

Whenever you gain life, you may put that many +1/+1 counters on each creature you control. Do this only once each turn.

Getting

Smothering Tithe

Whenever an opponent draws a card, that player may pay {2}. If the player doesn't, you create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Sunscorch Regent

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

Crawlspace

No more than two creatures can attack you each combat.

The Book of Exalted Deeds

At the beginning of your end step, if you gained 3 or more life this turn, create a 3/3 white Angel creature token with flying.
{W}{W}{W}, {T}, Exile The Book of Exalted Deeds: Put an enlightened counter on target Angel. It gains "You can't lose the game and your opponents can't win the game." Activate only as a sorcery.

Divinity of Pride

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

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.

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.

Plains

Cleric of Life's Bond

Whenever another Cleric you control enters, you gain 1 life.
Whenever you gain life for the first time each turn, put a +1/+1 counter on Cleric of Life's Bond.

Soul Warden

Whenever another creature enters, you gain 1 life.

Cliffhaven Vampire

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

Greed

Swords to Plowshares

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

Windfall

Each player discards their hand, then draws cards equal to the greatest number of cards a player discarded this way.

Godless Shrine

({T}: Add {W} or {B}.)
As Godless Shrine enters, you may pay 2 life. If you don't, it enters tapped.

Celestial Unicorn

Whenever you gain life, put a +1/+1 counter on Celestial Unicorn.

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.

Twinblade Paladin

Whenever you gain life, put a +1/+1 counter on Twinblade Paladin.
As long as you have 25 or more life, Twinblade Paladin has double strike. (It deals both first-strike and regular combat damage.)

Polluted Delta

{T}, Pay 1 life, Sacrifice Polluted Delta: Search your library for an Island or Swamp card, put it onto the battlefield, then shuffle.

Arcane Signet

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

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.

Swamp

Demonic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.

Indulging Patrician

Flying
Lifelink (Damage dealt by this creature also causes you to gain that much life.)
At the beginning of your end step, if you gained 3 or more life this turn, each opponent loses 3 life.

Oloro, Ageless Ascetic

At the beginning of your upkeep, you gain 2 life.
Whenever you gain life, you may pay {1}. If you do, draw a card and each opponent loses 1 life.
At the beginning of your upkeep, if Oloro, Ageless Ascetic is in the command zone, you gain 2 life.

Liliana's Contract

When Liliana's Contract enters, you draw four cards and you lose 4 life.
At the beginning of your upkeep, if you control four or more Demons with different names, you win the game.

Dimir Signet

Mana Crypt

At the beginning of your upkeep, flip a coin. If you lose the flip, Mana Crypt deals 3 damage to you.
{T}: Add {C}{C}.

Light of Promise

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

Return to Dust

Exile target artifact or enchantment. If you cast this spell during your main phase, you may exile up to one other target artifact or enchantment.

Gifted Aetherborn

Fumigate

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

Griffin Aerie

At the beginning of your end step, if you gained 3 or more life this turn, create a 2/2 white Griffin creature token with flying.

Rhox Faithmender

Lifelink (Damage dealt by this creature also causes you to gain that much life.)
If you would gain life, you gain twice that much life instead.

Lim-Dûl's Vault

Look at the top five cards of your library. As many times as you choose, you may pay 1 life, put those cards on the bottom of your library in any order, then look at the top five cards of your library. Then shuffle and put the last cards you looked at this way on top in any order.

Island

Soul's Attendant

Whenever another creature enters, you may gain 1 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.

Obelisk of Esper

Underground Sea

Sensei's Divining Top

{1}: Look at the top three cards of your library, then put them back in any order.
{T}: Draw a card, then put Sensei's Divining Top on top of its owner's library.

Gideon's Company

Whenever you gain life, put two +1/+1 counters on Gideon's Company.
{3}{W}: Put a loyalty counter on target Gideon planeswalker.

Speaker of the Heavens

Vigilance, lifelink (Attacking doesn't cause this creature to tap. Damage dealt by this creature also causes you to gain that much life.)
{T}: Create a 4/4 white Angel creature token with flying. Activate only if you have at least 7 life more than your starting life total and only as a sorcery.

Azorius Signet

Tundra

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.

Cleric Class

(Gain the next level as a sorcery to add its ability.)
If you would gain life, you gain that much life plus 1 instead.
{3}{W}: Level 2
Whenever you gain life, put a +1/+1 counter on target creature you control.
{4}{W}: Level 3
When this Class becomes level 3, return target creature card from your graveyard to the battlefield. You gain life equal to that creature's toughness.

Ajani's Pridemate

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

Voice of the Blessed

Whenever you gain life, put a +1/+1 counter on Voice of the Blessed.
As long as Voice of the Blessed has four or more +1/+1 counters on it, it has flying and vigilance.
As long as Voice of the Blessed has ten or more +1/+1 counters on it, it has indestructible.

Archangel of Thune

Flying
Lifelink (Damage dealt by this creature also causes you to gain that much life.)
Whenever you gain life, put a +1/+1 counter on each creature you control.

Bloodthirsty Aerialist

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

Defiant Bloodlord

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

Felidar Sovereign

Vigilance (Attacking doesn't cause this creature to tap.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)
At the beginning of your upkeep, if you have 40 or more life, you win the game.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Flooded Strand

{T}, Pay 1 life, Sacrifice Flooded Strand: Search your library for a Plains or Island card, put it onto the battlefield, then shuffle.

Toxic Deluge

As an additional cost to cast this spell, pay X life.
All creatures get -X/-X until end of turn.

Talisman of Dominance

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

Angel of Destiny

Flying, double strike
Whenever a creature you control deals combat damage to a player, you and that player each gain that much life.
At the beginning of your end step, if you have at least 15 life more than your starting life total, each player Angel of Destiny attacked this turn loses the game.

Sanguine Bond

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

Pristine Talisman

Mystical Tutor

Search your library for an instant or sorcery card, reveal it, then shuffle and put that card on top.

Vampiric Tutor

Search your library for a card, then shuffle and put that card on top. You lose 2 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.

Attended Healer

Whenever you gain life for the first time each turn, create a 1/1 white Cat creature token.
{2}{W}: Another target Cleric gains lifelink until end of turn.

Enlightened Tutor

Search your library for an artifact or enchantment card, reveal it, then shuffle and put that card on top.

Radiant Fountain

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

Orzhov Signet

Watery Grave

({T}: Add {U} or {B}.)
As Watery Grave enters, you may pay 2 life. If you don't, it enters tapped.

Talisman of Progress

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

Authority of the Consuls

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

Ajani's Welcome

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

Sigarda's Splendor

As Sigarda's Splendor enters, note your life total.
At the beginning of your upkeep, draw a card if your life total is greater than or equal to the last noted life total for Sigarda's Splendor. Then note your life total.
Whenever you cast a white spell, you gain 1 life.

Fountain of Renewal

At the beginning of your upkeep, you gain 1 life.
{3}, Sacrifice Fountain of Renewal: Draw a card.

Sol Ring

Marsh Flats

{T}, Pay 1 life, Sacrifice Marsh Flats: Search your library for a Plains or Swamp card, put it onto the battlefield, then shuffle.

Hallowed Fountain

({T}: Add {W} or {U}.)
As Hallowed Fountain enters, you may pay 2 life. If you don't, it enters tapped.

Kambal, Consul of Allocation

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

Beacon of Immortality

Double target player's life total. Shuffle Beacon of Immortality into its owner's library.

Exquisite Blood

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

Vault of Champions

Vault of Champions enters tapped unless you have two or more opponents.
{T}: Add {W} or {B}.

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

Scrubland

Survival Cache

You gain 2 life. Then if you have more life than an opponent, draw a card.
Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)