Yawgmoth, Thran Physician

Protection from Humans
Pay 1 life, Sacrifice another creature: Put a -1/-1 counter on up to one target creature and draw a card.
{B}{B}, Discard a card: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Shadow-Rite Priest

Other Clerics you control get +1/+1.
{3}{B}{B}, {T}, Sacrifice another Cleric: Search your library for a black creature card, put it onto the battlefield, then shuffle.

Venser's Journal

You have no maximum hand size.
At the beginning of your upkeep, you gain 1 life for each card in your hand.

Goremand

As an additional cost to cast this spell, sacrifice a creature.
Flying
Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
When this creature enters, each opponent sacrifices a creature.

Xathrid Necromancer

Whenever this creature or another Human creature you control dies, create a tapped 2/2 black Zombie creature token.

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Demonlord of Ashmouth

Flying
When this creature enters, 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.)

Attrition

{B}, Sacrifice a creature: Destroy target nonblack creature.

Sceptre of Eternal Glory

{T}: Add one mana of any color.
{T}: Add three mana of any one color. Activate only if you control three or more lands with the same name.

Krav, the Unredeemed

Partner with Regna, the Redeemer (When this creature enters, target player may put Regna into their hand from their library, then shuffle.)
{B}, Sacrifice X creatures: Target player draws X cards and gains X life. Put X +1/+1 counters on Krav.

Reliquary Tower

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

Venomcrawler

Lifelink
Devourer of Souls — Whenever another creature dies, put a +1/+1 counter on this creature.

Swamp

Foul Rebirth

Sacrifice a non-Demon creature. If you do, create a 4/3 white and black Vampire Demon creature token with flying.

Promise of Aclazotz

At the beginning of your end step, you may sacrifice a non-Demon creature. If you do, populate. (Create a token that's a copy of a creature token you control.)

Promise of Aclazotz // Foul Rebirth

Dark Prophecy

Whenever a creature you control dies, you draw a card and you lose 1 life.

Dictate of Erebos

Flash
Whenever a creature you control dies, each opponent sacrifices a creature of their choice.

Skirsdag High Priest

Morbid — {T}, Tap two untapped creatures you control: Create a 5/5 black Demon creature token with flying. Activate only if a creature died this turn.

Echoing Return

Return target creature card and all other cards with the same name as that card from your graveyard to your hand.

Archdemon of Greed

Flying, trample
At the beginning of your upkeep, sacrifice a Human. If you can't, tap this creature and it deals 9 damage to you.

Ravenous Demon

Sacrifice a Human: Transform this creature. Activate only as a sorcery.

Ravenous Demon // Archdemon of Greed

Promise of Power

Choose one —
• You draw five cards and you lose 5 life.
• Create an X/X black Demon creature token with flying, where X is the number of cards in your hand.
Entwine {4} (Choose both if you pay the entwine cost.)

Ormendahl, the Corrupter

Flying, trample, lifelink
Sacrifice another creature: Draw a card.

Jerren, Corrupted Bishop

Whenever Jerren enters or another nontoken Human you control dies, you lose 1 life and create a 1/1 white Human creature token.
{2}: Target Human you control gains lifelink until end of turn.
At the beginning of your end step, if you have exactly 13 life, you may pay {4}{B}{B}. If you do, transform Jerren.

Jerren, Corrupted Bishop // Ormendahl, the Corrupter

Plumb the Forbidden

As an additional cost to cast this spell, you may sacrifice one or more creatures. When you do, copy this spell for each creature sacrificed this way.
You draw a card and you lose 1 life.

Harvester of Souls

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Whenever another nontoken creature dies, you may draw a card.

Ob Nixilis, Unshackled

Flying, trample
Whenever an opponent searches their library, that player sacrifices a creature of their choice and loses 10 life.
Whenever another creature dies, put a +1/+1 counter on Ob Nixilis.

Razaketh, the Foulblooded

Flying, trample
Pay 2 life, Sacrifice another creature: Search your library for a card, put that card into your hand, then shuffle.

The Speed Demon

Flying, trample
Start your engines! (If you have no speed, it starts at 1. It increases once on each of your turns when an opponent loses life. Max speed is 4.)
At the beginning of your end step, you draw X cards and lose X life, where X is your speed.

Feaster of Fools

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Flying
Devour 2 (As this creature enters, you may sacrifice any number of creatures. It enters with twice that many +1/+1 counters on it.)

Vilis, Broker of Blood

Flying
{B}, Pay 2 life: Target creature gets -1/-1 until end of turn.
Whenever you lose life, draw that many cards. (Damage causes loss of life.)

Ritual Chamber

When you unlock this door, create a 6/6 black Demon creature token with flying.
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Unholy Annex

At the beginning of your end step, draw a card. If you control a Demon, each opponent loses 2 life and you gain 2 life. Otherwise, you lose 2 life.
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Unholy Annex // Ritual Chamber

Village Rites

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Vile Mutilator

As an additional cost to cast this spell, sacrifice a creature or enchantment.
Flying, trample
When this creature enters, each opponent sacrifices a nontoken enchantment of their choice, then sacrifices a nontoken creature of their choice.

Shadowborn Apostle

A deck can have any number of cards named Shadowborn Apostle.
{B}, Sacrifice six creatures named Shadowborn Apostle: Search your library for a Demon creature card, put it onto the battlefield, then shuffle.

Demon of Catastrophes

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

Demonic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Bankrupt in Blood

As an additional cost to cast this spell, sacrifice two creatures.
Draw three cards.

Tevesh Szat, Doom of Fools

+2: Create two 0/1 black Thrull creature tokens.
+1: You may sacrifice another creature or planeswalker. If you do, draw two cards, then draw another card if the sacrificed permanent was a commander.
−10: Gain control of all commanders. Put all commanders from the command zone onto the battlefield under your control.
Tevesh Szat, Doom of Fools can be your commander.
Partner

Corrupted Conviction

Secret Salvage

Exile target nonland card from your graveyard. Search your library for any number of cards with the same name as that card, reveal them, put them into your hand, then shuffle.

Eater of Hope

Flying
{B}, Sacrifice another creature: Regenerate this creature.
{2}{B}, Sacrifice two other creatures: Destroy target creature.

Ormendahl, Profane Prince

Westvale Abbey

{T}: Add {C}.
{5}, {T}, Pay 1 life: Create a 1/1 white and black Human Cleric creature token.
{5}, {T}, Sacrifice five creatures: Transform this land, then untap it.

Westvale Abbey // Ormendahl, Profane Prince

Reaper from the Abyss

Flying
Morbid — At the beginning of each end step, if a creature died this turn, destroy target non-Demon creature.

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

Decanter of Endless Water

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

Taborax, Hope's Demise

Flying
Taborax has lifelink as long as it has five or more +1/+1 counters on it.
Whenever another nontoken creature you control dies, put a +1/+1 counter on Taborax. If that creature was a Cleric, you may draw a card. If you do, you lose 1 life.

Dreadfeast Demon

Flying
At the beginning of your end step, sacrifice a non-Demon creature. If you do, create a token that's a copy of this creature.

Thought Vessel

Grave Pact

Whenever a creature you control dies, each other player sacrifices a creature of their choice.