Dazzling Angel

Flying
Whenever another creature 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.

Exquisite Blood

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

Soul's Attendant

Whenever another creature enters, you may 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.

Ajani's Pridemate

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

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.

Elenda, Saint of Dusk

Lifelink, hexproof from instants
As long as your life total is greater than your starting life total, Elenda gets +1/+1 and has menace. Elenda gets an additional +5/+5 as long as your life total is at least 10 greater than your starting life total.

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.

Aetherflux Reservoir

Whenever you cast a spell, you gain 1 life for each spell you've cast this turn.
Pay 50 life: This artifact deals 50 damage to any target.

The Gaffer

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

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.

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.

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.

Soul of Innistrad

Deathtouch
{3}{B}{B}: Return up to three target creature cards from your graveyard to your hand.
{3}{B}{B}, Exile this card from your graveyard: Return up to three target creature cards from your graveyard to your hand.

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.

Sanguine Bond

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

Authority of the Consuls

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

Enduring Tenacity

Whenever you gain life, target opponent loses that much life.
When Enduring Tenacity dies, if it was a creature, return it to the battlefield under its owner's control. It's an enchantment. (It's not a creature.)

Soul Warden

Whenever another creature enters, you gain 1 life.

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.

Essence Warden

Moldervine Reclamation

Whenever a creature you control dies, you gain 1 life and draw a card.

Beacon of Immortality

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