Archfiend of Despair

Flying
Your opponents can't gain life.
At the beginning of each end step, each opponent loses life equal to the life that player lost this turn. (Damage causes loss of life.)

Apocalypse Demon

Flying
Apocalypse Demon's power and toughness are each equal to the number of cards in your graveyard.
At the beginning of your upkeep, tap Apocalypse Demon unless you sacrifice another creature.

Ob Nixilis, Captive Kingpin

Flying, trample
Whenever one or more opponents each lose exactly 1 life, put a +1/+1 counter on Ob Nixilis, Captive Kingpin. Exile the top card of your library. Until your next end step, you may play that card.

Archdemon of Greed

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

Ravenous Demon

Sacrifice a Human: Transform Ravenous Demon. Activate only as a sorcery.

Ravenous Demon // Archdemon of Greed

Harvester of Souls

Deathtouch
Whenever another nontoken creature dies, you may draw a card.

Xathrid Demon

Flying, trample
At the beginning of your upkeep, sacrifice a creature other than Xathrid Demon, then each opponent loses life equal to the sacrificed creature's power. If you can't sacrifice a creature, tap Xathrid Demon and you lose 7 life.

Archfiend of Spite

Flying
Whenever a source an opponent controls deals damage to Archfiend of Spite, that source's controller loses that much life unless they sacrifice that many permanents.
Madness {3}{B}{B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Human Cleric

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Demon

Flying, trample
At the beginning of your upkeep, sacrifice another creature. If you can't, this creature deals 6 damage to you.

Demon's Grasp

Target creature gets -5/-5 until end of turn.

Archfiend of Depravity

Flying
At the beginning of each opponent's end step, that player chooses up to two creatures they control, then sacrifices the rest.

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.

Demonic Hordes

{T}: Destroy target land.
At the beginning of your upkeep, unless you pay {B}{B}{B}, tap Demonic Hordes and sacrifice a land of an opponent's choice.

Cleric

Plague Wind

Destroy all creatures you don't control. They can't be regenerated.

Awoken Demon

Ecstatic Awakener

{2}{B}, Sacrifice another creature: Draw a card, then transform Ecstatic Awakener. Activate only once each turn.

Ecstatic Awakener // Awoken Demon

Shadowgrange Archfiend

When Shadowgrange Archfiend enters, each opponent sacrifices a creature with the greatest power among creatures they control. You gain life equal to the greatest power among creatures sacrificed this way.
Madness—{2}{B}, Pay 8 life. (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Demon Berserker

Menace (This creature can't be blocked except by two or more creatures.)

Westvale Cult Leader

Westvale Cult Leader's power and toughness are each equal to the number of creatures you control.
At the beginning of your end step, create a 1/1 white and black Human Cleric creature token.

Hanweir Militia Captain

At the beginning of your upkeep, if you control four or more creatures, transform Hanweir Militia Captain.

Hanweir Militia Captain // Westvale Cult Leader

Grave Pact

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

Demonic Counsel

Search your library for a Demon card, reveal it, put it into your hand, then shuffle.
Delirium — If there are four or more card types among cards in your graveyard, instead search your library for any card, put it into your hand, then shuffle.