Demon of Catastrophes

As an additional cost to cast this spell, sacrifice a creature.
Flying, trample

Defiant Bloodlord

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

Kuon's Essence

At the beginning of each player's upkeep, that player sacrifices a creature.

Kuon, Ogre Ascendant

At the beginning of the end step, if three or more creatures died this turn, flip Kuon, Ogre Ascendant.

Kuon, Ogre Ascendant // Kuon's Essence

Arcane Signet

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

Demon's Disciple

When Demon's Disciple enters the battlefield, each player sacrifices a creature or planeswalker.

Swamp

Jungle Hollow

Jungle Hollow enters the battlefield tapped.
When Jungle Hollow enters the battlefield, you gain 1 life.
{T}: Add {B} or {G}.

Kheru Bloodsucker

Whenever a creature you control with toughness 4 or greater dies, each opponent loses 2 life and you gain 2 life.
{2}{B}, Sacrifice another creature: Put a +1/+1 counter on Kheru Bloodsucker.

Lampad of Death's Vigil

{1}, Sacrifice a creature: Each opponent loses 1 life and you gain 1 life.

Mossbeard Ancient

Trample
When Mossbeard Ancient enters the battlefield, you gain 5 life.

Vindictive Vampire

Whenever another creature you control dies, Vindictive Vampire deals 1 damage to each opponent and you gain 1 life.

Serrated Scorpion

When Serrated Scorpion dies, it deals 2 damage to each opponent and you gain 2 life.

Witch of the Moors

Deathtouch
At the beginning of your end step, if you gained life this turn, each opponent sacrifices a creature and you return up to one target creature card from your graveyard to your hand.

Whisper, Blood Liturgist

{T}, Sacrifice two creatures: Return target creature card from your graveyard to the battlefield.

Forest

Gutless Ghoul

{1}, Sacrifice a creature: You gain 2 life.

Reclamation Sage

When Reclamation Sage enters the battlefield, you may destroy target artifact or enchantment.

Savra, Queen of the Golgari

Whenever you sacrifice a black creature, you may pay 2 life. If you do, each other player sacrifices a creature.
Whenever you sacrifice a green creature, you may gain 2 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.

Centaur Nurturer

When Centaur Nurturer enters the battlefield, you gain 3 life.
{T}: Add one mana of any color.

Desecration Demon

Flying
At the beginning of each combat, any opponent may sacrifice a creature. If a player does, tap Desecration Demon and put a +1/+1 counter on it.

Willowdusk, Essence Seer

{1}, {T}: Choose another target creature. Put a number of +1/+1 counters on it equal to the amount of life you gained this turn or the amount of life you lost this turn, whichever is greater. Activate only as a sorcery.

Scion of the Swarm

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

Veinwitch Coven

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

Bramble Wurm

Reach, trample
When Bramble Wurm enters the battlefield, you gain 5 life.
{2}{G}, Exile Bramble Wurm from your graveyard: You gain 5 life.

Demonlord of Ashmouth

Flying
When Demonlord of Ashmouth enters the battlefield, exile it unless you sacrifice another creature.
Undying (When this creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

Sol Ring

Blood Host

{1}{B}, Sacrifice another creature: Put a +1/+1 counter on Blood Host and you gain 2 life.

Priest of Forgotten Gods

{T}, Sacrifice two other creatures: Any number of target players each lose 2 life and sacrifice a creature. You add {B}{B} and draw a card.

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Ayara, First of Locthwain

Whenever Ayara, First of Locthwain or another black creature enters the battlefield under your control, each opponent loses 1 life and you gain 1 life.
{T}, Sacrifice another black creature: Draw a card.

Plaguecrafter

When Plaguecrafter enters the battlefield, each player sacrifices a creature or planeswalker. Each player who can't discards a card.

Vengeant Vampire

Lifelink
When Vengeant Vampire dies, destroy target creature an opponent controls and you gain 4 life.

Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.

Demon of Death's Gate

You may pay 6 life and sacrifice three black creatures rather than pay this spell's mana cost.
Flying, trample

Bloodborn Scoundrels

Assist (Another player can pay up to {5} of this spell's cost.)
When Bloodborn Scoundrels enters the battlefield, target opponent loses 2 life and you gain 2 life.

Bloodbond Vampire

Whenever you gain life, put a +1/+1 counter on Bloodbond Vampire.

Abyssal Gatekeeper

When Abyssal Gatekeeper dies, each player sacrifices a creature.

Leyline Prowler

Deathtouch, lifelink
{T}: Add one mana of any color.

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.

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Doomed Necromancer

{B}, {T}, Sacrifice Doomed Necromancer: Return target creature card from your graveyard to the battlefield.

Golgari Rot Farm

Golgari Rot Farm enters the battlefield tapped.
When Golgari Rot Farm enters the battlefield, return a land you control to its owner's hand.
{T}: Add {B}{G}.

Command Tower

Vermin Gorger

{T}, Sacrifice another creature: Each opponent loses 2 life and you gain 2 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.

Courier Bat

Flying
When Courier Bat enters the battlefield, if you gained life this turn, return up to one target creature card from your graveyard to your hand.

Zulaport Cutthroat

Whenever Zulaport Cutthroat or another creature you control dies, each opponent loses 1 life and you gain 1 life.

Vampire Spawn

When Vampire Spawn enters the battlefield, each opponent loses 2 life and you gain 2 life.

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.

Merciless Executioner

When Merciless Executioner enters the battlefield, each player sacrifices a creature.

Solemn Simulacrum

When Solemn Simulacrum enters the battlefield, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When Solemn Simulacrum dies, you may draw a card.

Starved Rusalka

{G}, Sacrifice a creature: You gain 1 life.

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

Decanter of Endless Water

You have no maximum hand size.
{T}: Add one mana of any color.

Demon of Wailing Agonies

Flying
Lieutenant — As long as you control your commander, Demon of Wailing Agonies gets +2/+2 and has "Whenever Demon of Wailing Agonies deals combat damage to a player, that player sacrifices a creature."

Sylvok Replica

{G}, Sacrifice Sylvok Replica: Destroy target artifact or enchantment.

Arborback Stomper

Trample
When Arborback Stomper enters the battlefield, you gain 5 life.

Bloodthirsty Aerialist

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

Chain Devil

Animate Chains — When Chain Devil enters the battlefield, each player sacrifices a nontoken creature.

Pelakka Wurm

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

Spore Frog

Sacrifice Spore Frog: Prevent all combat damage that would be dealt this turn.

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.

Dawnhart Rejuvenator

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

Vampire Scrivener

Flying
Whenever you gain life during your turn, put a +1/+1 counter on Vampire Scrivener.
Whenever you lose life during your turn, put a +1/+1 counter on Vampire Scrivener.

Fleshbag Marauder

When Fleshbag Marauder enters the battlefield, each player sacrifices a creature.

Knight of the Ebon Legion

{2}{B}: Knight of the Ebon Legion gets +3/+3 and gains deathtouch until end of turn.
At the beginning of your end step, if a player lost 4 or more life this turn, put a +1/+1 counter on Knight of the Ebon Legion. (Damage causes loss of life.)

Meren of Clan Nel Toth

Whenever another creature you control dies, you get an experience counter.
At the beginning of your end step, choose target creature card in your graveyard. If that card's mana value is less than or equal to the number of experience counters you have, return it to the battlefield. Otherwise, put it into your hand.

Bushmeat Poacher

{1}, {T}, Sacrifice another creature: You gain life equal to the sacrificed creature's toughness. Draw a card.

Hell's Caretaker

{T}, Sacrifice a creature: Return target creature card from your graveyard to the battlefield. Activate only during your upkeep.

Fabled Passage

{T}, Sacrifice Fabled Passage: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Then if you control four or more lands, untap that land.

Ageless Entity

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

Demon of Loathing

Flying, trample
Whenever Demon of Loathing deals combat damage to a player, that player sacrifices a creature.

Disciple of Griselbrand

{1}, Sacrifice a creature: You gain life equal to the sacrificed creature's toughness.