Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.

Forest

Blood Researcher

Menace (This creature can't be blocked except by two or more creatures.)
Whenever you gain life, put a +1/+1 counter on Blood Researcher.

Essence Warden

Whenever another creature enters, you gain 1 life.

Ill-Gotten Inheritance

At the beginning of your upkeep, Ill-Gotten Inheritance deals 1 damage to each opponent and you gain 1 life.
{5}{B}, Sacrifice Ill-Gotten Inheritance: It deals 4 damage to target opponent and you gain 4 life.

Vampire Sovereign

Flying
When Vampire Sovereign enters, target opponent loses 3 life and you gain 3 life.

Cruel Grimnarch

Deathtouch
When Cruel Grimnarch enters, each opponent discards a card. For each opponent who can't, you gain 4 life.

Dina, Soul Steeper

Whenever you gain life, each opponent loses 1 life.
{1}, Sacrifice another creature: Dina, Soul Steeper gets +X/+0 until end of turn, where X is the sacrificed creature's power.

Specter of the Fens

Flying
{5}{B}: Target opponent loses 2 life and you gain 2 life.

Gray Merchant of Asphodel

When Gray Merchant of Asphodel 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.)

Herald of Hadar

Circle of Death — {5}{B}: Roll a d20.
1—9 | Each opponent loses 2 life.
10—19 | Each opponent loses 2 life and you gain 2 life.
20 | Each opponent loses 2 life and you gain 2 life. Create two Treasure tokens. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Blood Tithe

Each opponent loses 3 life. You gain life equal to the life lost this way.

Orchard Elemental

Council's dilemma — When Orchard Elemental enters, starting with you, each player votes for sprout or harvest. Put two +1/+1 counters on Orchard Elemental for each sprout vote. You gain 3 life for each harvest vote.

Vampire Opportunist

{6}{B}: Each opponent loses 2 life and you gain 2 life.

Syphon Mind

Each other player discards a card. You draw a card for each card discarded this way.

Flourishing Hunter

When Flourishing Hunter enters, you gain life equal to the greatest toughness among other creatures you control.

Swamp

Golgari Signet

Garrulous Sycophant

At the beginning of your end step, if you're the monarch, each opponent loses 1 life and you gain 1 life.

Thorn of the Black Rose

Deathtouch
When Thorn of the Black Rose enters, you become the monarch.

Filigree Familiar

When Filigree Familiar enters, you gain 2 life.
When Filigree Familiar dies, draw a card.

Infuse with Vitality

Until end of turn, target creature gains deathtouch and "When this creature dies, return it to the battlefield tapped under its owner's control."
You gain 2 life.

Vampire Envoy

Flying
Whenever Vampire Envoy becomes tapped, you gain 1 life.

Entourage of Trest

When Entourage of Trest enters, you become the monarch.
Entourage of Trest can block an additional creature each combat as long as you're the monarch.

Creeping Bloodsucker

At the beginning of your upkeep, Creeping Bloodsucker deals 1 damage to each opponent. You gain life equal to the damage dealt this way.

Epicure of Blood

Vampire Neonate

{2}, {T}: Each opponent loses 1 life and you gain 1 life.

Vegetation Abomination

Deathtouch
{T}, Sacrifice Vegetation Abomination: Roll a six-sided die. You gain life equal to the result.

Witherbloom Pledgemage

Magecraft — Whenever you cast or copy an instant or sorcery spell, you gain 1 life.

Jaddi Offshoot

Defender
Landfall — Whenever a land you control enters, you gain 1 life.

Syphon Soul

Syphon Soul deals 2 damage to each other player. You gain life equal to the damage dealt this way.

Kazandu Nectarpot

Landfall — Whenever a land you control enters, you gain 1 life.

Gloom Sower

Whenever Gloom Sower becomes blocked by a creature, that creature's controller loses 2 life and you gain 2 life.

Dogged Pursuit

At the beginning of your end step, each opponent loses 1 life and you gain 1 life.

Diregraf Scavenger

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
When Diregraf Scavenger enters, exile up to one target card from a graveyard. If a creature card was exiled this way, each opponent loses 2 life and you gain 2 life.

Urborg Repossession

Kicker {1}{G} (You may pay an additional {1}{G} as you cast this spell.)
Return target creature card from your graveyard to your hand. You gain 2 life. If this spell was kicked, return another target permanent card from your graveyard to your hand.

Dawnhart Rejuvenator

When Dawnhart Rejuvenator enters, you gain 3 life.
{T}: Add one mana of any color.

Deathgreeter

Whenever another creature dies, you may gain 1 life.

Tamiyo's Safekeeping

Target permanent you control gains hexproof and indestructible until end of turn. You gain 2 life. (A permanent with hexproof and indestructible can't be the target of spells or abilities your opponents control. Damage and effects that say "destroy" don't destroy it.)

Luxa River Shrine

{1}, {T}: You gain 1 life. Put a brick counter on Luxa River Shrine.
{T}: You gain 2 life. Activate only if there are three or more brick counters on Luxa River Shrine.

Pulse of Murasa

Return target creature or land card from a graveyard to its owner's hand. You gain 6 life.

Avenging Hunter

Trample
When Avenging Hunter enters, you take the initiative.

Vampire Spawn

When this creature enters, each opponent loses 2 life and you gain 2 life.

Passageway Seer

Lifelink
When Passageway Seer enters, you take the initiative.
At the beginning of your end step, if you have the initiative, put a +1/+1 counter on Passageway Seer.

Vicious Battlerager

When Vicious Battlerager enters, you take the initiative.
Spiked Retribution — Whenever Vicious Battlerager becomes blocked by a creature, that creature's controller loses 5 life.

Nexus Wardens

Reach
Constellation — Whenever an enchantment you control enters, you gain 2 life.

Pristine Talisman

Arcane Signet

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

Grazing Gladehart

Landfall — Whenever a land you control enters, you may gain 2 life.

Sanguine Indulgence

This spell costs {3} less to cast if you've gained 3 or more life this turn.
Return up to two target creature cards from your graveyard to your hand.