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.

Ajani's Pridemate

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

Orzhov Signet

Scion of the Swarm

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

Drogskol Reaver

Flying
Double strike (This creature deals both first-strike and regular combat damage.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)
Whenever you gain life, draw a card.

Nyx-Fleece Ram

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

Heroes Remembered

You gain 20 life.
Suspend 10—{W} (Rather than cast this card from your hand, you may pay {W} and exile it with ten time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)

Wurm's Tooth

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

Hulking Metamorph

Prototype {2}{U}{U} — 3/3 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.)
You may have this creature enter as a copy of an artifact or creature you control, except it's an artifact creature in addition to its other types, and its power and toughness are equal to this creature's power and toughness.

Clock of Omens

Tap two untapped artifacts you control: Untap target artifact.

Swamp

Seraph Sanctuary

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

Vampire Scrivener

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

Soul's Attendant

Whenever another creature enters, you may gain 1 life.

God-Pharaoh's Faithful

Whenever you cast a blue, black, or red spell, you gain 1 life.

Angel's Feather

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

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.

Plains

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.

Azorius Signet

Debt to the Deathless

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

Sculpting Steel

You may have this artifact enter as a copy of any artifact on the battlefield.

Noble Purpose

Whenever a creature you control deals combat damage, you gain that much 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.

Light of Promise

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

Authority of the Consuls

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

Soul Warden

Whenever another creature enters, you gain 1 life.

Beacon of Immortality

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

Dimir Signet

Gideon's Company

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

Mirage Mirror

{2}: This artifact becomes a copy of target artifact, creature, enchantment, or land until end of turn.

Kraken's Eye

Whenever a player casts a blue spell, you may gain 1 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.

Rodolf Duskbringer

Flying, deathtouch, lifelink
Whenever you gain life, Rodolf Duskbringer gains indestructible until end of turn.
At the beginning of your end step, you may pay {1}{W/B}. When you do, return target creature card with mana value X or less from your graveyard to the battlefield, where X is the amount of life you gained this turn.

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.

Sanguine Bond

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

Fumigate

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

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.

Wedding Ring

When this artifact enters, if it was cast, target opponent creates a token that's a copy of it.
Whenever an opponent who controls an artifact named Wedding Ring draws a card during their turn, you draw a card.
Whenever an opponent who controls an artifact named Wedding Ring gains life during their turn, you gain that much life.

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.

Swords to Plowshares

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

The Mycosynth Gardens

{T}: Add {C}.
{1}, {T}: Add one mana of any color.
{X}, {T}: This land becomes a copy of target nontoken artifact you control with mana value X.

Yavimaya, Cradle of Growth

Each land is a Forest in addition to its other land types.

The Gaffer

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

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.

Dragon's Claw

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

Wall of Limbs

Defender (This creature can't attack.)
Whenever you gain life, put a +1/+1 counter on this creature.
{5}{B}{B}, Sacrifice this creature: Target player loses X life, where X is this creature's power.

Sanctimony

Whenever an opponent taps a Mountain for mana, you may gain 1 life.

Wall of Hope

Defender (This creature can't attack.)
Whenever this creature is dealt damage, you gain that much 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 is in the command zone, you gain 2 life.

Arcane Signet

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

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.

Queza, Augur of Agonies

Whenever you draw a card, target opponent loses 1 life and you gain 1 life.

Scrib Nibblers

{T}: Exile the top card of target player's library. If it's a land card, you gain 1 life.
Landfall — Whenever a land you control enters, you may untap this creature.

Lifetap

Whenever a Forest an opponent controls becomes tapped, you gain 1 life.

Sol Ring

Commander's Sphere

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

Elenda's Hierophant

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

Emissary of Hope

Flying
Whenever this creature deals combat damage to a player, you gain 1 life for each artifact that player controls.

Bloodthirsty Aerialist

Demon's Horn

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

Celestial Unicorn

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Will, Scion of Peace

Vigilance
{T}: Spells you cast this turn that are white and/or blue cost {X} less to cast, where X is the amount of life you gained this turn. Activate only as a sorcery.

Urza, Prince of Kroog

Artifact creatures you control get +2/+2.
{6}: Create a token that's a copy of target artifact you control, except it's a 1/1 Soldier creature in addition to its other types.

Epicure of Blood

Whenever you gain life, each opponent loses 1 life.

Bloodbond Vampire

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.)