Sanguine Syphoner

Whenever this creature attacks, each opponent loses 1 life and you gain 1 life.

Swamp

Etched Host Doombringer

When Etched Host Doombringer enters, choose one —
• Target opponent loses 2 life and you gain 2 life.
• Choose target battle. If an opponent protects it, remove three defense counters from it. Otherwise, put three defense counters on it.

Vraan, Executioner Thane

Whenever one or more other creatures you control die, each opponent loses 2 life and you gain 2 life. This ability triggers only once each turn.

Etched Familiar

When Etched Familiar dies, each opponent loses 2 life and you gain 2 life.

Glidedive Duo

Flying
When Glidedive Duo enters, each opponent loses 2 life and you gain 2 life.

Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.

Vengeful Bloodwitch

Whenever this creature or another creature you control dies, target opponent loses 1 life and you gain 1 life.

Pulse Tracker

Whenever this creature attacks, each opponent loses 1 life.

Friendly Teddy

When Friendly Teddy dies, each player draws a card.

Blightbelly Rat

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
When Blightbelly Rat dies, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Dune Mover

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
When Dune Mover enters, you may search your library for a basic land card, reveal it, then shuffle and put that card on top.

Fear of Lost Teeth

When Fear of Lost Teeth dies, it deals 1 damage to any target and you gain 1 life.

Bilious Skulldweller

Deathtouch
Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)

Vein Ripper

Flying
Ward—Sacrifice a creature.
Whenever a creature dies, target opponent loses 2 life and you gain 2 life.

Agate-Blade Assassin

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

Dreg Recycler

{T}, Sacrifice an artifact or creature: Each opponent loses 1 life and you gain 1 life.