Awaken the Erstwhile

Each player discards all the cards in their hand, then creates that many 2/2 black Zombie creature tokens.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

Burglar Rat

When Burglar Rat enters the battlefield, each opponent discards a card.

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.

Sheoldred, Whispering One

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
At the beginning of your upkeep, return target creature card from your graveyard to the battlefield.
At the beginning of each opponent's upkeep, that player sacrifices a creature.

Tergrid's Lantern

{T}: Target player loses 3 life unless they sacrifice a nonland permanent or discard a card.
{3}{B}: Untap Tergrid's Lantern.

Tergrid, God of Fright

Menace
Whenever an opponent sacrifices a nontoken permanent or discards a permanent card, you may put that card from a graveyard onto the battlefield under your control.

Tergrid, God of Fright // Tergrid's Lantern

Gix's Command

Choose two —
• Put two +1/+1 counters on up to one creature. It gains lifelink until end of turn.
• Destroy each creature with power 2 or less.
• Return up to two creature cards from your graveyard to your hand.
• Each opponent sacrifices a creature with the highest power among creatures they control.

Dark Ritual

Malakir Mire

Malakir Mire enters the battlefield tapped.
{T}: Add {B}.

Malakir Rebirth

Choose target creature. You lose 2 life. Until end of turn, that creature gains "When this creature dies, return it to the battlefield tapped under its owner's control."

Malakir Rebirth // Malakir Mire

Innocent Blood

Bottomless Pit

At the beginning of each player's upkeep, that player discards a card at random.

Sudden Edict

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Target player sacrifices a creature.

Feed the Swarm

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

Syphon Mind

Each other player discards a card. You draw a card for each card discarded this way.

Smallpox

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

Liliana's Triumph

Each opponent sacrifices a creature. If you control a Liliana planeswalker, each opponent also discards a card.

Mire in Misery

Each opponent sacrifices a creature or enchantment.

Make an Example

Each opponent separates the creatures they control into two piles. For each opponent, you choose one of their piles. Each opponent sacrifices the creatures in their chosen pile. (Piles can be empty.)

Jet Medallion

Black spells you cast cost {1} less to cast.

Mind Rake

Target player discards two cards.
Overload {1}{B} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Bojuka Bog

Bojuka Bog enters the battlefield tapped.
When Bojuka Bog enters the battlefield, exile target player's graveyard.
{T}: Add {B}.

Soul Shatter

Each opponent sacrifices a creature or planeswalker with the highest mana value among creatures and planeswalkers they control.

Elderfang Disciple

When Elderfang Disciple enters the battlefield, each opponent discards a card.

Virus Beetle

When Virus Beetle enters the battlefield, each opponent discards a card.

Braids, Arisen Nightmare

At the beginning of your end step, you may sacrifice an artifact, creature, enchantment, land, or planeswalker. If you do, each opponent may sacrifice a permanent that shares a card type with it. For each opponent who doesn't, that player loses 2 life and you draw a card.

Dark Deal

Each player discards all the cards in their hand, then draws that many cards minus one.

Castle Locthwain

Castle Locthwain enters the battlefield tapped unless you control a Swamp.
{T}: Add {B}.
{1}{B}{B}, {T}: Draw a card, then you lose life equal to the number of cards in your hand.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Fleshbag Marauder

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

Sol Ring

Swamp

Vicious Rumors

Vicious Rumors deals 1 damage to each opponent. Each opponent discards a card, then mills a card. You gain 1 life.

Tourach, Dread Cantor

Kicker {B}{B} (You may pay an additional {B}{B} as you cast this spell.)
Protection from white
Whenever an opponent discards a card, put a +1/+1 counter on Tourach, Dread Cantor.
When Tourach enters the battlefield, if it was kicked, target opponent discards two cards at random.

Court of Ambition

When Court of Ambition enters the battlefield, you become the monarch.
At the beginning of your upkeep, each opponent loses 3 life unless they discard a card. If you're the monarch, instead each opponent loses 6 life unless they discard two cards.

Fraying Omnipotence

Each player loses half their life, then discards half the cards in their hand, then sacrifices half the creatures they control. Round up each time.

Demon's Disciple

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

Infernal Idol

{T}: Add {B}.
{1}{B}{B}, {T}, Sacrifice Infernal Idol: You draw two cards and you lose 2 life.

Portal to Phyrexia

When Portal to Phyrexia enters the battlefield, each opponent sacrifices three creatures.
At the beginning of your upkeep, put target creature card from a graveyard onto the battlefield under your control. It's a Phyrexian in addition to its other types.

Nykthos, Shrine to Nyx

{T}: Add {C}.
{2}, {T}: Choose a color. Add an amount of mana of that color equal to your devotion to that color. (Your devotion to a color is the number of mana symbols of that color in the mana costs of permanents you control.)

The Eldest Reborn

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Each opponent sacrifices a creature or planeswalker.
II — Each opponent discards a card.
III — Put target creature or planeswalker card from a graveyard onto the battlefield under your control.

The Raven Man

At the beginning of each end step, if a player discarded a card this turn, create a 1/1 black Bird creature token with flying and "This creature can't block."
{3}{B}, {T}: Each opponent discards a card. Activate only as a sorcery.

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.

Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters the battlefield, 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.)

Sign in Blood

Target player draws two cards and loses 2 life.

Arcane Signet

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

Merciless Executioner

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

Geier Reach Sanitarium

{T}: Add {C}.
{2}, {T}: Each player draws a card, then discards a card.

Charcoal Diamond

Charcoal Diamond enters the battlefield tapped.
{T}: Add {B}.

Plaguecrafter

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

Sangromancer

Flying
Whenever a creature an opponent controls dies, you may gain 3 life.
Whenever an opponent discards a card, you may gain 3 life.

Geth's Grimoire

Whenever an opponent discards a card, you may draw a card.

Megrim

Whenever an opponent discards a card, Megrim deals 2 damage to that player.

Liliana, Waker of the Dead

+1: Each player discards a card. Each opponent who can't loses 3 life.
−3: Target creature gets -X/-X until end of turn, where X is the number of cards in your graveyard.
−7: You get an emblem with "At the beginning of combat on your turn, put target creature card from a graveyard onto the battlefield under your control. It gains haste."

Necrogoyf

Necrogoyf's power is equal to the number of creature cards in all graveyards.
At the beginning of each player's upkeep, that player discards a card.
Madness {1}{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.)