Feed the Serpent

Bloodsoaked Reveler

At the beginning of your end step, if you gained life this turn, create a Blood token. (It's an artifact with "{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.")
{4}{B}: Each opponent loses 2 life and you gain 2 life.

Restless Bloodseeker

At the beginning of your end step, if you gained life this turn, create a Blood token. (It's an artifact with "{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.")
Sacrifice two Blood tokens: Transform Restless Bloodseeker. Activate only as a sorcery.

Restless Bloodseeker // Bloodsoaked Reveler

Spore Crawler

Sporecrown Thallid

Each other creature you control that's a Fungus or Saproling gets +1/+1.

Yavimaya Sapherd

When Yavimaya Sapherd enters the battlefield, create a 1/1 green Saproling creature token.

Withercrown

Enchant creature
Enchanted creature has base power 0 and has "At the beginning of your upkeep, you lose 1 life unless you sacrifice this creature."

Geth's Verdict

Target player sacrifices a creature and loses 1 life.

Annihilating Glare

As an additional cost to cast this spell, pay {4} or sacrifice an artifact or creature.
Destroy target creature or planeswalker.

Saproling Migration

Kicker {4} (You may pay an additional {4} as you cast this spell.)
Create two 1/1 green Saproling creature tokens. If this spell was kicked, create four of those tokens instead.

Saproling Symbiosis

You may cast Saproling Symbiosis as though it had flash if you pay {2} more to cast it. (You may cast it any time you could cast an instant.)
Create a 1/1 green Saproling creature token for each creature you control.

Parasitic Impetus

Enchant creature
Enchanted creature gets +2/+2 and is goaded. (It attacks each combat if able and attacks a player other than you if able.)
Whenever enchanted creature attacks, its controller loses 2 life and you gain 2 life.

Hunt for Specimens

Create a 1/1 black and green Pest creature token with "When this creature dies, you gain 1 life."
Learn. (You may reveal a Lesson card you own from outside the game and put it into your hand, or discard a card to draw a card.)

Blood Artist

Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.

Falkenrath Noble

Flying
Whenever Falkenrath Noble or another creature dies, target player loses 1 life and you gain 1 life.

Spore Swarm

Create three 1/1 green Saproling creature tokens.

Pitiless Plunderer

Whenever another creature you control dies, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Vampirism

Enchant creature
When Vampirism enters the battlefield, draw a card at the beginning of the next turn's upkeep.
Enchanted creature gets +1/+1 for each other creature you control.
Other creatures you control get -1/-1.

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Maul Splicer

When Maul Splicer enters the battlefield, create two 3/3 colorless Phyrexian Golem artifact creature tokens.
Golem creatures you control have trample.

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.

Bladebrand

Target creature gains deathtouch until end of turn.
Draw a card.

Thallid

At the beginning of your upkeep, put a spore counter on Thallid.
Remove three spore counters from Thallid: Create a 1/1 green Saproling creature token.

Exquisite Blood

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

Mind Rot

Tainted Remedy

If an opponent would gain life, that player loses that much life instead.

Ashnod's Altar

Aetherflux Reservoir

Whenever you cast a spell, you gain 1 life for each spell you've cast this turn.
Pay 50 life: Aetherflux Reservoir deals 50 damage to any target.

Slimefoot, the Stowaway

Whenever a Saproling you control dies, Slimefoot, the Stowaway deals 1 damage to each opponent and you gain 1 life.
{4}: Create a 1/1 green Saproling creature token.

Ghave, Guru of Spores

Ghave, Guru of Spores enters the battlefield with five +1/+1 counters on it.
{1}, Remove a +1/+1 counter from a creature you control: Create a 1/1 green Saproling creature token.
{1}, Sacrifice a creature: Put a +1/+1 counter on target creature.

Dauntless Survivor

When Dauntless Survivor enters the battlefield, put a +1/+1 counter on target creature.

Phyrexian Altar

Sacrifice a creature: Add one mana of any color.

Epicure of Blood

Whenever you gain life, each opponent loses 1 life.

Pact Weapon

As long as Pact Weapon is attached to a creature, you don't lose the game for having 0 or less life.
Whenever equipped creature attacks, draw a card and reveal it. The creature gets +X/+X until end of turn and you lose X life, where X is that card's mana value.
Equip—Discard a card.

Sanguine Bond

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

Necrotic Fumes

As an additional cost to cast this spell, exile a creature you control.
Exile target creature or planeswalker.