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.

Blood Researcher

Menace (This creature can't be blocked except by two or more creatures.)
Whenever you gain life, put a +1/+1 counter on this creature.

Essence Warden

Whenever another creature enters, you gain 1 life.

Voice of the Blessed

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

Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Syndic of Tithes

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.)

Oketra's Monument

White creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, create a 1/1 white Warrior creature token with vigilance.

Sythis, Harvest's Hand

Whenever you cast an enchantment spell, you gain 1 life and draw a card.

Prosperous Innkeeper

When this creature enters, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")
Whenever another creature you control enters, you gain 1 life.

Tocasia's Welcome

Whenever one or more creatures you control with mana value 3 or less enter, draw a card. This ability triggers only once each turn.

Elas il-Kor, Sadistic Pilgrim

Deathtouch
Whenever another creature you control enters, you gain 1 life.
Whenever another creature you control dies, each opponent loses 1 life.

Dawn of Hope

Whenever you gain life, you may pay {2}. If you do, draw a card.
{3}{W}: Create a 1/1 white Soldier creature token with lifelink.

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.

Impassioned Orator

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

Wayward Disciple

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

Pious Evangel

Whenever this creature or another creature you control enters, you gain 1 life.
{2}, {T}, Sacrifice another permanent: Transform this creature.

Pious Evangel // Wayward Disciple

Forest

Social Climber

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

Trespasser's Curse

Enchant player
Whenever a creature enchanted player controls enters, that player loses 1 life and you gain 1 life.

Answered Prayers

Whenever a creature you control enters, you gain 1 life. If this enchantment isn't a creature, it becomes a 3/3 Angel creature with flying in addition to its other types until end of turn.

Soul Link

Enchant creature
Whenever enchanted creature deals damage, you gain that much life.
Whenever enchanted creature is dealt damage, you gain that much life.

Trelasarra, Moon Dancer

Whenever you gain life, put a +1/+1 counter on Trelasarra and scry 1. (Look at the top card of your library. You may put that card on the bottom.)

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.

Rumor Gatherer

Alliance — Whenever another creature you control enters, scry 1. If this is the second time this ability has resolved this turn, draw a card instead.

Soul Warden

Lifelink

Enchant creature
Enchanted creature has lifelink. (Damage dealt by the creature also causes its controller to gain that much life.)

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.

Orzhov Signet

Kambal, Consul of Allocation

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

Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.

Gala Greeters

Alliance — Whenever another creature you control enters, choose one that hasn't been chosen this turn —
• Put a +1/+1 counter on this creature.
• Create a tapped Treasure token.
• You gain 2 life.

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 this creature.

Karlov of the Ghost Council

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

Spirit Link

Enchant creature (Target a creature as you cast this. This card enters attached to that creature.)
Whenever enchanted creature deals damage, you gain that much life.

Celestial Unicorn

Whenever you gain life, put a +1/+1 counter on this creature.

Angelic Chorus

Whenever a creature you control enters, you gain life equal to its toughness.

Plains

Sol Ring

Dina, Soul Steeper

Whenever you gain life, each opponent loses 1 life.
{1}, Sacrifice another creature: Dina gets +X/+0 until end of turn, where X is the sacrificed creature's power.

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.

Vampiric Link

Enchant creature
Whenever enchanted creature deals damage, you gain that much life.

Spirit Loop

Enchant creature you control
Whenever enchanted creature deals damage, you gain that much life.
When this Aura is put into a graveyard from the battlefield, return it to its owner's hand.

Distinguished Conjurer

Whenever another creature you control enters, you gain 1 life.
{4}{W}, {T}: Exile another target creature you control, then return it to the battlefield under its owner's control.

Bilbo, Birthday Celebrant

If you would gain life, you gain that much life plus 1 instead.
{2}{W}{B}{G}, {T}, Exile Bilbo: Search your library for any number of creature cards, put them onto the battlefield, then shuffle. Activate only if you have 111 or more life.

Cradle of Vitality

Whenever you gain life, you may pay {1}{W}. If you do, put a +1/+1 counter on target creature for each 1 life you gained.

Kor Celebrant

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

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.

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.

Light of Promise

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

Ajani's Pridemate

Ageless Entity

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

Bloodthirsty Aerialist

Flying
Whenever you gain life, put a +1/+1 counter on this creature.

Selesnya Signet

Twinblade Paladin

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

Luminous Phantom

Flying
Whenever another creature you control leaves the battlefield, you gain 1 life.
If Luminous Phantom would be put into a graveyard from anywhere, exile it instead.

Lunarch Veteran

Whenever another creature you control enters, you gain 1 life.
Disturb {1}{W} (You may cast this card from your graveyard transformed for its disturb cost.)

Lunarch Veteran // Luminous Phantom

Auriok Champion

Protection from black and from red
Whenever another creature enters, you may gain 1 life.

Swamp

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

Healer of the Pride

Whenever another creature you control enters, you gain 2 life.

Golgari Signet

Scion of the Swarm

Daxos, Blessed by the Sun

Daxos's toughness is equal to your devotion to white. (Each {W} in the mana costs of permanents you control counts toward your devotion to white.)
Whenever another creature you control enters or dies, you gain 1 life.

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.

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.

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.

Life Insurance

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 a nontoken creature dies, you lose 1 life and create a Treasure token.

Arcane Signet

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

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.

Tithe Drinker

Lifelink (Damage dealt by this creature also causes you to gain that much life.)
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.)