Zellix, Sanity Flayer

Hive Mind — Whenever a player mills one or more creature cards, you create a 1/1 black Horror creature token.
{1}, {T}: Target player mills three cards.
Choose a Background (You can have a Background as a second commander.)

Elder Brain

Menace
Whenever this creature attacks a player, exile all cards from that player's hand, then they draw that many cards. You may play lands and cast spells from among the exiled cards for as long as they remain exiled. If you cast a spell this way, you may spend mana as though it were mana of any color to cast it.

Grave Consequences

Each player may exile any number of cards from their graveyard. Then each player loses 1 life for each card in their graveyard.
Draw a card.

Tormod's Crypt

{T}, Sacrifice this artifact: Exile target player's graveyard.

Consuming Aberration

Consuming Aberration's power and toughness are each equal to the number of cards in your opponents' graveyards.
Whenever you cast a spell, each opponent reveals cards from the top of their library until they reveal a land card, then puts those cards into their graveyard.

Ashiok, Nightmare Muse

+1: Create a 2/3 blue and black Nightmare creature token with "Whenever this token attacks or blocks, each opponent exiles the top two cards of their library."
−3: Return target nonland permanent to its owner's hand, then that player exiles a card from their hand.
−7: You may cast up to three spells from among face-up cards your opponents own from exile without paying their mana costs.

Nihil Spellbomb

{T}, Sacrifice this artifact: Exile target player's graveyard.
When this artifact is put into a graveyard from the battlefield, you may pay {B}. If you do, draw a card.

Temple of Aclazotz

(Transforms from Arguel's Blood Fast.)
{T}: Add {B}.
{T}, Sacrifice a creature: You gain life equal to the sacrificed creature's toughness.

Arguel's Blood Fast

{1}{B}, Pay 2 life: Draw a card.
At the beginning of your upkeep, if you have 5 or less life, you may transform Arguel's Blood Fast.

Arguel's Blood Fast // Temple of Aclazotz

Sire of Stagnation

Devoid (This card has no color.)
Whenever a land an opponent controls enters, that player exiles the top two cards of their library and you draw two cards.

Psychic Symbiont

Flying
When this creature enters, target opponent discards a card and you draw a card.

Dimir Aqueduct

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {U}{B}.

Reliquary Tower

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

Traitor's Clutch

Target creature gets +1/+0, becomes black, and gains shadow until end of turn. (It can block or be blocked by only creatures with shadow.)
Flashback {1}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Swamp

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 of their choice that shares a card type with it. For each opponent who doesn't, that player loses 2 life and you draw a card.

Choked Estuary

As this land enters, you may reveal an Island or Swamp card from your hand. If you don't, this land enters tapped.
{T}: Add {U} or {B}.

Nemesis of Reason

Whenever this creature attacks, defending player mills ten cards.

Arcane Signet

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

Tainted Isle

{T}: Add {C}.
{T}: Add {U} or {B}. Activate only if you control a Swamp.

Dark Ritual

Ancient Cellarspawn

Each spell you cast that's a Demon, Horror, or Nightmare costs {1} less to cast.
Whenever you cast a spell, if the amount of mana spent to cast it was less than its mana value, target opponent loses life equal to the difference.

Scavenger Grounds

{T}: Add {C}.
{2}, {T}, Sacrifice a Desert: Exile all graveyards.

Lonely Sandbar

This land enters tapped.
{T}: Add {U}.
Cycling {U} ({U}, Discard this card: Draw a card.)

Whispersilk Cloak

Equipped creature can't be blocked and has shroud. (It can't be the target of spells or abilities.)
Equip {2}

Blot Out

Target opponent exiles a creature or planeswalker they control with the greatest mana value among creatures and planeswalkers they control.

River of Tears

{T}: Add {U}. If you played a land this turn, add {B} instead.

Doom Whisperer

Flying, trample
Pay 2 life: Surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Path of Ancestry

This land enters tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Creeping Inn

Whenever this creature attacks, you may exile a creature card from your graveyard. If you do, each opponent loses X life and you gain X life, where X is the number of creature cards exiled with Creeping Inn.
{4}: Creeping Inn phases out.

Hostile Hostel

{T}: Add {C}.
{1}, {T}, Sacrifice a creature: Put a soul counter on this land. Then if there are three or more soul counters on it, remove those counters, transform it, then untap it. Activate only as a sorcery.

Hostile Hostel // Creeping Inn

Reality Shift

Exile target creature. Its controller manifests the top card of their library. (That player puts the top card of their library onto the battlefield face down as a 2/2 creature. If it's a creature card, it can be turned face up any time for its mana cost.)

King Narfi's Betrayal

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Each player mills four cards. Then you may exile a creature or planeswalker card from each graveyard.
II, III — Until end of turn, you may cast spells from among cards exiled with this Saga, and you may spend mana as though it were mana of any color to cast those spells.

Murkwater Pathway

Clearwater Pathway

Clearwater Pathway // Murkwater Pathway

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Temple of Deceit

This land enters tapped.
When this land enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)
{T}: Add {U} or {B}.

Vraska's Contempt

Exile target creature or planeswalker. You gain 2 life.

Ashiok, Dream Render

Spells and abilities your opponents control can't cause their controller to search their library.
−1: Target player mills four cards. Then exile each opponent's graveyard.

Talisman of Dominance

{T}: Add {C}.
{T}: Add {U} or {B}. This artifact deals 1 damage to you.

Essence Harvest

Target player loses X life and you gain X life, where X is the greatest power among creatures you control.

Aether Tunnel

Enchant creature
Enchanted creature gets +1/+0 and can't be blocked.

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Chainer, Dementia Master

All Nightmares get +1/+1.
{B}{B}{B}, Pay 3 life: Put target creature card from a graveyard onto the battlefield under your control. That creature is black and is a Nightmare in addition to its other creature types.
When Chainer leaves the battlefield, exile all Nightmares.

Exotic Orchard

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

Defiler of Flesh

Menace
As an additional cost to cast black permanent spells, you may pay 2 life. Those spells cost {B} less to cast if you paid life this way. This effect reduces only the amount of black mana you pay.
Whenever you cast a black permanent spell, target creature you control gets +1/+1 and gains menace until end of turn.

Darkslick Shores

This land enters tapped unless you control two or fewer other lands.
{T}: Add {U} or {B}.

Rogue Class

(Gain the next level as a sorcery to add its ability.)
Whenever a creature you control deals combat damage to a player, exile the top card of that player's library face down. You may look at it for as long as it remains exiled.
{1}{U}{B}: Level 2
Creatures you control have menace.
{2}{U}{B}: Level 3
You may play cards exiled with this Class, and you may spend mana as though it were mana of any color to cast those spells.

Captain N'ghathrod

Horrors you control have menace.
Whenever a Horror you control deals combat damage to a player, that player mills that many cards.
At the beginning of your end step, choose target artifact or creature card in an opponent's graveyard that was put there from their library this turn. Put it onto the battlefield under your control.

Court of Cunning

When this enchantment enters, you become the monarch.
At the beginning of your upkeep, any number of target players each mill two cards. If you're the monarch, each of those players mills ten cards instead. (To mill a card, a player puts the top card of their library into their graveyard.)

Command Tower

Barren Moor

This land enters tapped.
{T}: Add {B}.
Cycling {B} ({B}, Discard this card: Draw a card.)

Ancient Craving

You draw three cards and you lose 3 life.

Temple of the False God

{T}: Add {C}{C}. Activate only if you control five or more lands.

Endless Evil

Enchant creature you control
At the beginning of your upkeep, create a token that's a copy of enchanted creature, except the token is 1/1.
When enchanted creature dies, if that creature was a Horror, return this card to its owner's hand.

Drowned Catacomb

This land enters tapped unless you control an Island or a Swamp.
{T}: Add {U} or {B}.

Nightmare Unmaking

Choose one —
• Exile each creature with power greater than the number of cards in your hand.
• Exile each creature with power less than the number of cards in your hand.

Fractured Sanity

Each opponent mills fourteen cards.
Cycling {1}{U} ({1}{U}, Discard this card: Draw a card.)
When you cycle this card, each opponent mills four cards.

Silent Hallcreeper

This creature can't be blocked.
Whenever this creature deals combat damage to a player, choose one that hasn't been chosen —
• Put two +1/+1 counters on this creature.
• Draw a card.
• This creature becomes a copy of another target creature you control.

Relic of Progenitus

{T}: Target player exiles a card from their graveyard.
{1}, Exile this artifact: Exile all graveyards. Draw a card.

Imperious Mindbreaker

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Imperious Mindbreaker is paired with another creature, each of those creatures has "Whenever this creature attacks, each opponent mills cards equal to its toughness."

Mind Funeral

Target opponent reveals cards from the top of their library until four land cards are revealed. That player puts all cards revealed this way into their graveyard.

Nightmare Shepherd

Flying
Whenever another nontoken creature you control dies, you may exile it. If you do, create a token that's a copy of that creature, except it's 1/1 and it's a Nightmare in addition to its other types.

Black Market

Whenever a creature dies, put a charge counter on this enchantment.
At the beginning of your first main phase, add {B} for each charge counter on this enchantment.

Nautiloid Ship

Flying
When this Vehicle enters, exile target player's graveyard.
Whenever this Vehicle deals combat damage to a player, you may put a creature card exiled with this Vehicle onto the battlefield under your control.
Crew 3

Grazilaxx, Illithid Scholar

Whenever a creature you control becomes blocked, you may return it to its owner's hand.
Whenever one or more creatures you control deal combat damage to a player, draw a card.

Crypt Incursion

Exile all creature cards from target player's graveyard. You gain 3 life for each card exiled this way.

Tasha's Hideous Laughter

Each opponent exiles cards from the top of their library until that player has exiled cards with total mana value 20 or more.

Phyrexian Obliterator

Trample
Whenever a source deals damage to this creature, that source's controller sacrifices that many permanents of their choice.

Fellwar Stone

Sol Ring

Spark Double

You may have this creature enter as a copy of a creature or planeswalker you control, except it enters with an additional +1/+1 counter on it if it's a creature, it enters with an additional loyalty counter on it if it's a planeswalker, and it isn't legendary.

Ashiok, Nightmare Weaver

+2: Exile the top three cards of target opponent's library.
−X: Put a creature card with mana value X exiled with Ashiok onto the battlefield under your control. That creature is a Nightmare in addition to its other types.
−10: Exile all cards from all opponents' hands and graveyards.

Persistent Nightmare

Skulk (This creature can't be blocked by creatures with greater power.)
When this creature deals combat damage to a player, return it to its owner's hand.

Startled Awake

Target opponent mills thirteen cards.
{3}{U}{U}: Put this card from your graveyard onto the battlefield transformed. Activate only as a sorcery.

Startled Awake // Persistent Nightmare

Toxic Deluge

As an additional cost to cast this spell, pay X life.
All creatures get -X/-X until end of turn.

Sludge Monster

Whenever this creature enters or attacks, put a slime counter on up to one other target creature.
Non-Horror creatures with slime counters on them lose all abilities and have base power and toughness 2/2.

Gloomlake Verge

{T}: Add {U}.
{T}: Add {B}. Activate only if you control an Island or a Swamp.

Phyrexian Arena

At the beginning of your upkeep, you draw a card and you lose 1 life.

Nephalia Drownyard

{T}: Add {C}.
{1}{U}{B}, {T}: Target player mills three cards.

Yarok's Fenlurker

When this creature enters, each opponent exiles a card from their hand.
{2}{B}: This creature gets +1/+1 until end of turn.

Dimir Signet

Umbris, Fear Manifest

Umbris gets +1/+1 for each card your opponents own in exile.
Whenever Umbris or another Nightmare or Horror you control enters, target opponent exiles cards from the top of their library until they exile a land card.

Wharf Infiltrator

Skulk (This creature can't be blocked by creatures with greater power.)
Whenever this creature deals combat damage to a player, you may draw a card. If you do, discard a card.
Whenever you discard a creature card, you may pay {2}. If you do, create a 3/2 colorless Eldrazi Horror creature token.

Phyrexian Rager

When this creature enters, you draw a card and you lose 1 life.

Leyline of the Void

If this card is in your opening hand, you may begin the game with it on the battlefield.
If a card would be put into an opponent's graveyard from anywhere, exile it instead.

Sunken Hollow

({T}: Add {U} or {B}.)
This land enters tapped unless you control two or more basic lands.

Dauthi Embrace

{B}{B}: Target creature gains shadow until end of turn. (It can block or be blocked by only creatures with shadow.)

Bojuka Bog

This land enters tapped.
When this land enters, exile target player's graveyard.
{T}: Add {B}.

The Mindskinner

The Mindskinner can't be blocked.
If a source you control would deal damage to an opponent, prevent that damage and each opponent mills that many cards.

Ravenous Chupacabra

When this creature enters, destroy target creature an opponent controls.

Uchuulon

Uchuulon's power is equal to the number of Crabs, Oozes, and/or Horrors you control.
Horrific Symbiosis — At the beginning of your end step, exile up to one target creature card from an opponent's graveyard. If you do, create a token that's a copy of this creature.