Scion of the Swarm

Flying
Whenever you gain life, put a +1/+1 counter on Scion of the Swarm.

Uro, Titan of Nature's Wrath

When Uro enters the battlefield, sacrifice it unless it escaped.
Whenever Uro enters the battlefield or attacks, you gain 3 life and draw a card, then you may put a land card from your hand onto the battlefield.
Escape—{G}{G}{U}{U}, Exile five other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)

Phyrexian Gargantua

When Phyrexian Gargantua enters the battlefield, you draw two cards and you lose 2 life.

Grazing Gladehart

Landfall — Whenever a land enters the battlefield under your control, you may gain 2 life.

Jaddi Offshoot

Defender
Landfall — Whenever a land enters the battlefield under your control, you gain 1 life.

Illusions of Grandeur

Cumulative upkeep {2} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
When Illusions of Grandeur enters the battlefield, you gain 20 life.
When Illusions of Grandeur leaves the battlefield, you lose 20 life.

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.

Ikra Shidiqi, the Usurper

Menace
Whenever a creature you control deals combat damage to a player, you gain life equal to that creature's toughness.
Partner (You can have two commanders if both have partner.)

Druid Class

(Gain the next level as a sorcery to add its ability.)
Landfall — Whenever a land enters the battlefield under your control, you gain 1 life.
{2}{G}: Level 2
You may play an additional land on each of your turns.
{4}{G}: Level 3
When this Class becomes level 3, target land you control becomes a creature with haste and "This creature's power and toughness are each equal to the number of lands you control." It's still a land.

Courser of Kruphix

Play with the top card of your library revealed.
You may play lands from the top of your library.
Landfall — Whenever a land enters the battlefield under your control, you gain 1 life.

Bloodthirsty Aerialist

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

Sanguine Bond

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

Primeval Bounty

Whenever you cast a creature spell, create a 3/3 green Beast creature token.
Whenever you cast a noncreature spell, put three +1/+1 counters on target creature you control.
Landfall — Whenever a land enters the battlefield under your control, you gain 3 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.

Dark Confidant

At the beginning of your upkeep, reveal the top card of your library and put that card into your hand. You lose life equal to its mana value.

Hydroid Krasis

When you cast this spell, you gain half X life and draw half X cards. Round down each time.
Flying, trample
Hydroid Krasis enters the battlefield with X +1/+1 counters on it.

Sifter Wurm

Trample
When Sifter Wurm enters the battlefield, scry 3, then reveal the top card of your library. You gain life equal to that card's mana value.

Healer of the Glade

When Healer of the Glade enters the battlefield, you gain 3 life.

Phyrexian Delver

When Phyrexian Delver enters the battlefield, return target creature card from your graveyard to the battlefield. You lose life equal to that card's mana value.

Pelakka Wurm

Trample
When Pelakka Wurm enters the battlefield, you gain 7 life.
When Pelakka Wurm dies, draw a card.

Lifegift

Whenever a land enters the battlefield, you may gain 1 life.

Bookwurm

Trample
When Bookwurm enters the battlefield, you gain 3 life and draw a card.
{2}{G}: Put Bookwurm from your graveyard into your library third from the top.

Poisonbelly Ogre

Whenever another creature enters the battlefield, its controller loses 1 life.

Trufflesnout

When Trufflesnout enters the battlefield, choose one —
• Put a +1/+1 counter on Trufflesnout.
• You gain 4 life.

Ageless Entity

Whenever you gain life, put that many +1/+1 counters on Ageless Entity.

Defiant Bloodlord

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

Selkie Hedge-Mage

When Selkie Hedge-Mage enters the battlefield, if you control two or more Forests, you may gain 3 life.
When Selkie Hedge-Mage enters the battlefield, if you control two or more Islands, you may return target tapped creature to its owner's hand.

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.

Archon of Cruelty

Flying
Whenever Archon of Cruelty enters the battlefield or attacks, target opponent sacrifices a creature or planeswalker, discards a card, and loses 3 life. You draw a card and gain 3 life.

Wall of Limbs

Defender (This creature can't attack.)
Whenever you gain life, put a +1/+1 counter on Wall of Limbs.
{5}{B}{B}, Sacrifice Wall of Limbs: Target player loses X life, where X is Wall of Limbs's power.

Retreat to Hagra

Landfall — Whenever a land enters the battlefield under your control, choose one —
• Target creature gets +1/+0 and gains deathtouch until end of turn.
• Each opponent loses 1 life and you gain 1 life.

Leyline of Vitality

If Leyline of Vitality is in your opening hand, you may begin the game with it on the battlefield.
Creatures you control get +0/+1.
Whenever a creature enters the battlefield under your control, you may gain 1 life.

Yarok, the Desecrated

Deathtouch, lifelink
If a permanent entering the battlefield causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Delusions of Mediocrity

When Delusions of Mediocrity enters the battlefield, you gain 10 life.
When Delusions of Mediocrity leaves the battlefield, you lose 10 life.

Tatyova, Benthic Druid

Landfall — Whenever a land enters the battlefield under your control, you gain 1 life and draw a card.

Dusk Legion Zealot

When Dusk Legion Zealot enters the battlefield, you draw a card and you lose 1 life.

Kazandu Nectarpot

Landfall — Whenever a land enters the battlefield under your control, you gain 1 life.

Callous Bloodmage

When Callous Bloodmage enters the battlefield, choose one —
• Create a 1/1 black and green Pest creature token with "When this creature dies, you gain 1 life."
• You draw a card and you lose 1 life.
• Exile target player's graveyard.

Verdant Sun's Avatar

Whenever Verdant Sun's Avatar or another creature enters the battlefield under your control, you gain life equal to that creature's toughness.

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.

Epicure of Blood

Whenever you gain life, each opponent loses 1 life.

Dread Presence

Whenever a Swamp enters the battlefield under your control, choose one —
• You draw a card and you lose 1 life.
• Dread Presence deals 2 damage to any target and you gain 2 life.

Trespasser's Curse

Enchant player
Whenever a creature enters the battlefield under enchanted player's control, that player loses 1 life and you gain 1 life.

Lisette, Dean of the Root

Whenever you gain life, you may pay {1}. If you do, put a +1/+1 counter on each creature you control and those creatures gain trample until end of turn.

Valentin, Dean of the Vein

Menace, lifelink
If a nontoken creature an opponent controls would die, exile it instead. When you do, you may pay {2}. If you do, create a 1/1 black and green Pest creature token with "When this creature dies, you gain 1 life."

Valentin, Dean of the Vein // Lisette, Dean of the Root

Retreat to Kazandu

Landfall — Whenever a land enters the battlefield under your control, choose one —
• Put a +1/+1 counter on target creature.
• You gain 2 life.

Parasitic Strix

Flying
When Parasitic Strix enters the battlefield, if you control a black permanent, target player loses 2 life and you gain 2 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.

Polluted Bonds

Whenever a land enters the battlefield under an opponent's control, that player loses 2 life and you gain 2 life.

First-Sphere Gargantua

When First-Sphere Gargantua enters the battlefield, you draw a card and you lose 1 life.
Unearth {2}{B} ({2}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Marauding Blight-Priest

Blossoming Bogbeast

Whenever Blossoming Bogbeast attacks, you gain 2 life. Then creatures you control gain trample and get +X/+X until end of turn, where X is the amount of life you gained this turn.

Navigator's Compass

When Navigator's Compass enters the battlefield, you gain 3 life.
{T}: Until end of turn, target land you control becomes the basic land type of your choice in addition to its other types.

Veinwitch Coven

Menace
Whenever you gain life, you may pay {B}. If you do, return target creature card from your graveyard to your hand.

Prosperous Innkeeper

When Prosperous Innkeeper enters the battlefield, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Whenever another creature enters the battlefield under your control, you gain 1 life.

Noxious Gearhulk

Menace
When Noxious Gearhulk enters the battlefield, you may destroy another target creature. If a creature is destroyed this way, you gain life equal to its toughness.