Serra Ascendant

Lifelink (Damage dealt by this creature also causes you to gain that much life.)
As long as you have 30 or more life, this creature gets +5/+5 and has flying.

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.

Gray Merchant of Asphodel

When this creature enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Authority of the Consuls

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

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.

Exquisite Blood

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

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.

Blind Obedience

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Artifacts and creatures your opponents control enter tapped.

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.

Despark

Exile target permanent with mana value 4 or greater.

Liesa, Shroud of Dusk

Rather than pay {2} for each previous time you've cast this spell from the command zone this game, pay 2 life that many times.
Flying, lifelink
Whenever a player casts a spell, they lose 2 life.

Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.

Liesa, Forgotten Archangel

Flying, lifelink
Whenever another nontoken creature you control dies, return that card to its owner's hand at the beginning of the next end step.
If a creature an opponent controls would die, exile it instead.

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.)

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.

Soul Warden

Whenever another creature enters, you gain 1 life.

Bolas's Citadel

You may look at the top card of your library any time.
You may play lands and cast spells from the top of your library. If you cast a spell this way, pay life equal to its mana value rather than pay its mana cost.
{T}, Sacrifice ten nonland permanents: Each opponent loses 10 life.

Kambal, Consul of Allocation

Whenever an opponent casts a noncreature spell, that player loses 2 life and you gain 2 life.

Anguished Unmaking

Exile target nonland permanent. You lose 3 life.

Fell Mire

As this land enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {B}.

Fell the Profane

Fell the Profane // Fell Mire

Phyrexian Arena

At the beginning of your upkeep, you draw a card and you lose 1 life.

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.

Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Sanguine Bond

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

Swords to Plowshares

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

Caduceus, Staff of Hermes

Equipped creature has lifelink.
As long as you have 30 or more life, equipped creature gets +5/+5 and has indestructible and "Prevent all damage that would be dealt to this creature."
Equip {W}{W}