Nirkana Assassin

Whenever you gain life, Nirkana Assassin gains deathtouch until end of turn. (Any amount of damage it deals to a creature is enough to destroy it.)

Agate-Blade Assassin

Whenever Agate-Blade Assassin attacks, defending player loses 1 life and you gain 1 life.

Survive the Night

Target creature gets +1/+0 and gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)
Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Highway Robber

When Highway Robber enters, target opponent loses 2 life and you gain 2 life.

Angel of Renewal

Flying
When Angel of Renewal enters, you gain 1 life for each creature you control.

Lifecreed Duo

Flying
Whenever another creature you control enters, you gain 1 life.

Revitalize

Skymarch Bloodletter

Flying
When Skymarch Bloodletter enters, target opponent loses 1 life and you gain 1 life.

Kutzil's Flanker

Flash
When Kutzil's Flanker enters, choose one —
• Put a +1/+1 counter on Kutzil's Flanker for each creature that left the battlefield under your control this turn.
• You gain 2 life and scry 2.
• Exile target player's graveyard.

Fortified Rampart

Tenacity

Creatures you control get +1/+1 and gain lifelink until end of turn. Untap those creatures. (Damage dealt by those creatures also causes you to gain that much life.)

Kambal, Consul of Allocation

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

Courier Griffin

Flying
When Courier Griffin enters, you gain 2 life.

Thornplate Intimidator

Offspring {3} (You may pay an additional {3} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
When this creature enters, target opponent loses 3 life unless they sacrifice a nonland permanent of their choice or discard a card.

Infectious Horror

Whenever Infectious Horror attacks, each opponent loses 2 life.

Call to the Feast

Create three 1/1 white Vampire creature tokens with lifelink.

Planar Outburst

Destroy all nonland creatures.
Awaken 4—{5}{W}{W}{W} (If you cast this spell for {5}{W}{W}{W}, also put four +1/+1 counters on target land you control and it becomes a 0/0 Elemental creature with haste. It's still a land.)

Epicure of Blood

Whenever you gain life, each opponent loses 1 life.

Reave Soul

Destroy target creature with power 3 or less.

Child of Night

Night Market Lookout

Whenever Night Market Lookout becomes tapped, each opponent loses 1 life and you gain 1 life.

Safe Passage

Prevent all damage that would be dealt to you and creatures you control this turn.

Dawn's Truce

Gift a card (You may promise an opponent a gift as you cast this spell. If you do, they draw a card before its other effects.)
You and permanents you control gain hexproof until end of turn. If the gift was promised, permanents you control also gain indestructible until end of turn.

Sovereign's Bite

Target player loses 3 life and you gain 3 life.

Vampire Neonate

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

Last Kiss

Last Kiss deals 2 damage to target creature and you gain 2 life.

Bishop's Soldier

Lifelink (Damage dealt by this creature also causes you to gain that much life.)