Inner Demon

Enchant creature
Enchanted creature gets +2/+2, has flying, and is a Demon in addition to its other types.
When this Aura enters, all non-Demon creatures get -2/-2 until end of turn.

Graveshifter

Changeling (This card is every creature type.)
When this creature enters, you may return target creature card from your graveyard to your hand.

Ambition's Cost

You draw three cards and you lose 3 life.

Murder

Tendrils of Corruption

Tendrils of Corruption deals X damage to target creature and you gain X life, where X is the number of Swamps you control.

Disfigure

Target creature gets -2/-2 until end of turn.

Quest for the Gravelord

Whenever a creature dies, you may put a quest counter on this enchantment.
Remove three quest counters from this enchantment and sacrifice it: Create a 5/5 black Zombie Giant creature token.

Innocent Blood

Each player sacrifices a creature of their choice.

Priest of the Blood Rite

When this creature enters, create a 5/5 black Demon creature token with flying.
At the beginning of your upkeep, you lose 2 life.

Doom Blade

Carrier Thrall

When this creature dies, create a 1/1 colorless Eldrazi Scion creature token. It has "Sacrifice this token: Add {C}."

Foul Imp

Flying
When this creature enters, you lose 2 life.

Liliana's Contract

When this enchantment enters, you draw four cards and you lose 4 life.
At the beginning of your upkeep, if you control four or more Demons with different names, you win the game.

Grim Discovery

Choose one or both —
• Return target creature card from your graveyard to your hand.
• Return target land card from your graveyard to your hand.

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.

Gray Merchant of Asphodel

When this creature enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Changeling Outcast

Changeling (This card is every creature type.)
This creature can't block and can't be blocked.

Leechridden Swamp

({T}: Add {B}.)
This land enters tapped.
{B}, {T}: Each opponent loses 1 life. Activate only if you control two or more black permanents.

Mindwrack Demon

Flying, trample
When this creature enters, mill four cards.
Delirium — At the beginning of your upkeep, you lose 4 life unless there are four or more card types among cards in your graveyard.

Unhallowed Pact

Enchant creature
When enchanted creature dies, return that card to the battlefield under your control.

Smallpox

Each player loses 1 life, discards a card, sacrifices a creature of their choice, then sacrifices a land of their choice.

Ob Nixilis Reignited

+1: You draw a card and you lose 1 life.
−3: Destroy target creature.
−8: Target opponent gets an emblem with "Whenever a player draws a card, you lose 2 life."

Demonlord Belzenlok

Flying, trample
When Demonlord Belzenlok enters, exile cards from the top of your library until you exile a nonland card, then put that card into your hand. If the card's mana value is 4 or greater, repeat this process. Demonlord Belzenlok deals 1 damage to you for each card put into your hand this way.

Altar's Reap

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

Swamp

Blistergrub

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
When this creature dies, each opponent loses 2 life.

Demon of Loathing

Flying, trample
Whenever this creature deals combat damage to a player, that player sacrifices a creature of their choice.

Fetid Imp

Flying
{B}: This creature gains deathtouch until end of turn. (Any amount of damage it deals to a creature is enough to destroy it.)

Pestilence Demon

Flying
{B}: This creature deals 1 damage to each creature and each player.

Dread Return

Return target creature card from your graveyard to the battlefield.
Flashback—Sacrifice three creatures. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Desecration Demon

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

Indulgent Tormentor

Flying
At the beginning of your upkeep, draw a card unless target opponent sacrifices a creature of their choice or pays 3 life.