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.

Swamp

Leaden Myr

Orzhov Signet

Impassioned Orator

Whenever another creature you control enters, you 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.

Monk Realist

When Monk Realist enters, destroy target enchantment.

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

Wayward Disciple

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

Pious Evangel

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

Pious Evangel // Wayward Disciple

Contemplation

Whenever you cast a spell, you gain 1 life.

Hallowed Priest

Whenever you gain life, put a +1/+1 counter on Hallowed Priest.

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.

Bloodthirsty Aerialist

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

Kor Celebrant

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

Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Priest of Ancient Lore

When Priest of Ancient Lore enters, you gain 1 life and draw a card.

Scholar of Athreos

{2}{B}: Each opponent loses 1 life. You gain life equal to the life lost this way.

Answered Prayers

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

Orzhov Locket

{T}: Add {W} or {B}.
{W/B}{W/B}{W/B}{W/B}, {T}, Sacrifice Orzhov Locket: Draw two cards.

Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.

Doubtless One

Doubtless One's power and toughness are each equal to the number of Clerics on the battlefield.
Whenever Doubtless One deals damage, you gain that much life.

Benevolent Bodyguard

Sacrifice Benevolent Bodyguard: Target creature you control gains protection from the color of your choice until end of turn.

Plains

Marble Diamond

Marble Diamond enters tapped.
{T}: Add {W}.

Bloodbond Vampire

Whenever you gain life, put a +1/+1 counter on Bloodbond Vampire.

Healer of the Pride

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

Soul Warden

Whenever another creature enters, you gain 1 life.

Children of Korlis

Sacrifice Children of Korlis: You gain life equal to the life you've lost this turn. (Damage causes loss of life.)

Dawnbringer Cleric

When Dawnbringer Cleric enters, choose one —
• Cure Wounds — You gain 2 life.
• Dispel Magic — Destroy target enchantment.
• Gentle Repose — Exile target card from a graveyard.

Ajani's Pridemate

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

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Epicure of Blood

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.

Soulmender

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.

Charcoal Diamond

Charcoal Diamond enters tapped.
{T}: Add {B}.

Stone Haven Medic

Gold Myr

Celestial Unicorn

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

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.)