Shamanic Revelation

Draw a card for each creature you control.
Ferocious — You gain 4 life for each creature you control with power 4 or greater.

Hamza, Guardian of Arashin

This spell costs {1} less to cast for each creature you control with a +1/+1 counter on it.
Creature spells you cast cost {1} less to cast for each creature you control with a +1/+1 counter on it.

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.

Plains

Storm Herd

Create X 1/1 white Pegasus creature tokens with flying, where X is your life total.

Faith's Fetters

Enchant permanent
When Faith's Fetters enters, you gain 4 life.
Enchanted permanent can't attack or block, and its activated abilities can't be activated unless they're mana abilities.

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.

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.

Qala, Ajani's Pridemate

Whenever Qala, Ajani's Pridemate attacks, other attacking creatures you control get +X/+0 until end of turn, where X is the number of counters on Qala.
Whenever you gain life, put a +1/+1 counter on Qala.
{3}{W}: You gain 1 life.

Heliod's Intervention

Choose one —
• Destroy X target artifacts and/or enchantments.
• Target player gains twice X life.

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.

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.

Trostani, Selesnya's Voice

Whenever another creature you control enters, you gain life equal to that creature's toughness.
{1}{G}{W}, {T}: Populate. (Create a token that's a copy of a creature token you control.)

Tenacity

Creatures you control get +1/+1 and gain lifelink until end of turn. Untap those creatures. (Damage dealt by those creatures also causes you to gain that much life.)

Kazandu Nectarpot

Landfall — Whenever a land you control enters, you gain 1 life.

Exemplar of Light

Flying
Whenever you gain life, put a +1/+1 counter on this creature.
Whenever you put one or more +1/+1 counters on this creature, draw a card. This ability triggers only once each turn.

Adamant Will

Target creature gets +2/+2 and gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Cat Collector

When this creature enters, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
Whenever you gain life for the first time during each of your turns, create a 1/1 white Cat creature token.

Conclave Mentor

If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on that creature instead.
When Conclave Mentor dies, you gain life equal to its power.

Elenda's Hierophant

Flying
Whenever you gain life, put a +1/+1 counter on Elenda's Hierophant.
When Elenda's Hierophant dies, create X 1/1 white Vampire creature tokens with lifelink, where X is its power.

Hardened Scales

If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on it instead.

Ajani's Pridemate

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

Kutzil, Malamet Exemplar

Your opponents can't cast spells during your turn.
Whenever one or more creatures you control each with power greater than its base power deals combat damage to a player, draw a card.

Grazing Gladehart

Landfall — Whenever a land you control enters, you may gain 2 life.

Trelasarra, Moon Dancer

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

Sol Ring

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.

Valkyrie Harbinger

Flying
Lifelink (Damage dealt by this creature also causes you to gain that much life.)
At the beginning of each end step, if you gained 4 or more life this turn, create a 4/4 white Angel creature token with flying and vigilance.

Envoy of the Ancestors

Outlast {W} ({W}, {T}: Put a +1/+1 counter on this creature. Outlast only as a sorcery.)
Modified creatures you control have lifelink. (Equipment, Auras you control, and counters are modifications.)

Dusk Legion Duelist

Vigilance
Whenever one or more +1/+1 counters are put on Dusk Legion Duelist, draw a card. This ability triggers only once each turn.

Abzan Battle Priest

Outlast {W} ({W}, {T}: Put a +1/+1 counter on this creature. Outlast only as a sorcery.)
Each creature you control with a +1/+1 counter on it has lifelink.

Ajani, the Greathearted

Creatures you control have vigilance.
+1: You gain 3 life.
−2: Put a +1/+1 counter on each creature you control and a loyalty counter on each other planeswalker you control.

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.

Metropolis Reformer

Flying, vigilance
You have hexproof.
Whenever Metropolis Reformer is dealt damage, you gain that much life.

Take Up the Shield

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

Revitalize

Battlefield Promotion

Put a +1/+1 counter on target creature. That creature gains first strike until end of turn. You gain 2 life. (A creature with first strike deals combat damage before creatures without first strike.)

Accomplished Alchemist

{T}: Add one mana of any color.
{T}: Add X mana of any one color, where X is the amount of life you gained this turn.

Congregate

Target player gains 2 life for each creature on the battlefield.

Blossoming Bogbeast

Whenever Blossoming Bogbeast attacks, you gain 2 life. Then creatures you control gain trample and get +X/+X until end of turn, where X is the amount of life you gained this turn.

The Gaffer

At the beginning of each end step, if you gained 3 or more life this turn, draw a card.

Pledge of Unity

Put a +1/+1 counter on each creature you control. You gain 1 life for each creature you control.

Inspiring Call

Draw a card for each creature you control with a +1/+1 counter on it. Those creatures gain indestructible until end of turn. (Damage and effects that say "destroy" don't destroy them.)

Canopy Vista

({T}: Add {G} or {W}.)
Canopy Vista enters tapped unless you control two or more basic lands.

Light of Hope

Choose one —
• You gain 4 life.
• Destroy target enchantment.
• Put a +1/+1 counter on target creature.

Hurska Sweet-Tooth

Whenever Hurska Sweet-Tooth attacks, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain life.")
Whenever you gain life, you may pay {G/W}. When you do, target creature gets +X/+X until end of turn, where X is the amount of life you gained.

Command Tower

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

Light of Promise

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

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.

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.

Cosmic Rebirth

Choose target permanent card in your graveyard. If it has mana value 3 or less, you may put it onto the battlefield. If you don't put it onto the battlefield, put it into your hand.
You gain 3 life.

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.

Angel of Vitality

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

Forest

Ajani, Caller of the Pride

+1: Put a +1/+1 counter on up to one target creature.
−3: Target creature gains flying and double strike until end of turn.
−8: Create X 2/2 white Cat creature tokens, where X is your life total.

Essence Warden

Whenever another creature enters, you gain 1 life.

Lathiel, the Bounteous Dawn

Lifelink
At the beginning of each end step, if you gained life this turn, distribute up to that many +1/+1 counters among any number of other target creatures.

Arcane Signet

Sunpetal Grove

Sunpetal Grove enters tapped unless you control a Forest or a Plains.
{T}: Add {G} or {W}.

Moment of Heroism

Target creature gets +2/+2 and gains lifelink until end of turn. (Damage dealt by the creature also causes its controller to gain that much life.)

Soul Warden

Bond of Flourishing

Look at the top three cards of your library. You may reveal a permanent card from among them and put it into your hand. Put the rest on the bottom of your library in any order. You gain 3 life.

Retreat to Kazandu

Landfall — Whenever a land you control enters, choose one —
• Put a +1/+1 counter on target creature.
• You gain 2 life.

Fumigate

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

Celestial Unicorn

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

Divine Favor

Enchant creature
When Divine Favor enters, you gain 3 life.
Enchanted creature gets +1/+3.

Ancestor Dragon

Flying
Whenever one or more creatures you control attack, you gain 1 life for each attacking creature.

Shield Mare

Shield Mare can't be blocked by red creatures.
When Shield Mare enters or becomes the target of a spell or ability an opponent controls, you gain 3 life.

Sunscorch Regent

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

Orochi Merge-Keeper

{T}: Add {G}.
As long as Orochi Merge-Keeper is modified, it has "{T}: Add {G}{G}." (Equipment, Auras you control, and counters are modifications.)