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.

Pest Rescuer

At the beginning of each upkeep, if you don't control a Pest creature token, create a 1/1 black and green Pest creature token with "When this token dies, you gain 1 life."
If you would gain life, you gain that much life plus 1 instead.

Cauldron of Essence

Whenever a creature you control dies, each opponent loses 1 life and you gain 1 life.
{1}{B}{G}, {T}, Sacrifice a creature: Return target creature card from your graveyard to the battlefield. Activate only as a sorcery.

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.

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.

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.

Moseo, Vein's New Dean

Flying
When Moseo enters, create a 1/1 black and green Pest creature token with "Whenever this token attacks, you gain 1 life."
Infusion — At the beginning of your end step, if you gained life this turn, return up to one 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.

Soul Warden

Whenever another creature enters, you gain 1 life.

The Gaffer

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

Soul's Attendant

Whenever another creature enters, you may 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

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Studious First-Year

This creature enters prepared. (While it's prepared, you may cast a copy of its spell. Doing so unprepares it.)

Studious First-Year // Rampant Growth

Sign in Blood

Target player draws two cards and loses 2 life.

Scheming Silvertongue

Flying, lifelink
At the beginning of your second main phase, if you gained 2 or more life this turn, this creature becomes prepared. (While it's prepared, you may cast a copy of its spell. Doing so unprepares it.)

Scheming Silvertongue // Sign in Blood

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.