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

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.

Aqueous Form

Enchant creature
Enchanted creature can't be blocked.
Whenever enchanted creature attacks, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Temple of the False God

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

Ravenous Chupacabra

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

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.

Nighthowler

Bestow {2}{B}{B} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)
This creature and enchanted creature each get +X/+X, where X is the number of creature cards in all graveyards.

Arcane Signet

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

Done

Tap up to two target creatures. Those creatures don't untap during their controller's next untap step.

Said

Return target instant or sorcery card from your graveyard to your hand.

Said // Done

Skimming Strike

Tap up to one target creature. Draw a card. (Then shuffle this card into its owner's library.)

Dirgur Island Dragon

Flying
Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)

Dirgur Island Dragon // Skimming Strike

Increasing Confusion

Target player mills X cards. If this spell was cast from a graveyard, that player mills twice that many cards instead.
Flashback {X}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Spelltwine

Exile target instant or sorcery card from your graveyard and target instant or sorcery card from an opponent's graveyard. Copy those cards. Cast the copies if able without paying their mana costs. Exile Spelltwine.

Pit of Offerings

This land enters tapped.
When this land enters, exile up to three target cards from graveyards.
{T}: Add {C}.
{T}: Add one mana of any of the exiled cards' colors.

Drown in Dreams

Choose one. If you control a commander as you cast this spell, you may choose both instead.
• Target player draws X cards.
• Target player mills twice X cards.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice this artifact: Draw a card.

Essence Harvest

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

Syphon Mind

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

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}.

Devourer of Memory

Whenever one or more cards are put into your graveyard from your library, this creature gets +1/+1 until end of turn and can't be blocked this turn.
{1}{U}{B}: Mill a card.

Soul-Guide Lantern

When this artifact enters, exile target card from a graveyard.
{T}, Sacrifice this artifact: Exile each opponent's graveyard.
{1}, {T}, Sacrifice this artifact: Draw a card.

Aid the Fallen

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

Port of Karfell

This land enters tapped.
{T}: Add {U}.
{3}{U}{B}{B}, {T}, Sacrifice this land: Mill four cards, then return a creature card from your graveyard to the battlefield tapped. (To mill a card, put the top card of your library into your graveyard.)

Sign in Blood

Target player draws two cards and loses 2 life.

Screaming Swarm

Flying
Whenever you attack with one or more creatures, target player mills that many cards. (To mill a card, a player puts the top card of their library into their graveyard.)
{2}{U}: Put this card from your graveyard into your library second from the top.

Mystic Sanctuary

({T}: Add {U}.)
This land enters tapped unless you control three or more other Islands.
When this land enters untapped, you may put target instant or sorcery card from your graveyard on top of your library.

Reliquary Tower

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

Shared Trauma

Join forces — Starting with you, each player may pay any amount of mana. Each player mills X cards, where X is the total amount of mana paid this way.

Cadaver Lab

When you unlock this door, return target creature card from your graveyard to your hand.
(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.)

Defiled Crypt

Whenever one or more cards leave your graveyard, create a 2/2 black Horror enchantment creature token. This ability triggers only once each turn.
(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.)

Defiled Crypt // Cadaver Lab

Wayfarer's Bauble

{2}, {T}, Sacrifice this artifact: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Phyrexian Rager

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

Rite of Replication

Kicker {5} (You may pay an additional {5} as you cast this spell.)
Create a token that's a copy of target creature. If this spell was kicked, create five of those tokens instead.

Stream of Thought

Target player mills four cards. You shuffle up to four cards from your graveyard into your library.
Replicate {2}{U}{U} (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)

Dimir Keyrune

{T}: Add {U} or {B}.
{U}{B}: This artifact becomes a 2/2 blue and black Horror artifact creature until end of turn and can't be blocked this turn.

Banehound

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.

Displace

Exile up to two target creatures you control, then return those cards to the battlefield under their owner's control.

Dimir Guildgate

This land enters tapped.
{T}: Add {U} or {B}.

Swamp

Haunt of the Dead Marshes

When this creature enters, scry 1.
{2}{B}: Return this card from your graveyard to the battlefield tapped. Activate only if you control a legendary creature.

Inspiration from Beyond

Mill three cards, then return an instant or sorcery card from your graveyard to your hand.
Flashback {5}{U}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Sunken Hollow

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

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.

Evolving Wilds

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Myriad Landscape

This land enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice this land: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Nemesis of Reason

Whenever this creature attacks, defending player mills ten cards.

Fetid Pools

({T}: Add {U} or {B}.)
This land enters tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)

Fraying Sanity

Enchant player
At the beginning of each end step, enchanted player mills X cards, where X is the number of cards put into their graveyard from anywhere this turn.

Rogue's Passage

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

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}.

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.

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.)

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.

Go Blank

Target player discards two cards. Then exile that player's graveyard.

Reflections of Littjara

As this enchantment enters, choose a creature type.
Whenever you cast a spell of the chosen type, copy that spell. (A copy of a permanent spell becomes a token.)

The Ancient One

Descend 8 — The Ancient One can't attack or block unless there are eight or more permanent cards in your graveyard.
{2}{U}{B}: Draw a card, then discard a card. When you discard a card this way, target player mills cards equal to its mana value.

Tainted Isle

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

Jwar Isle Refuge

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {U} or {B}.

Midnight Clock

{T}: Add {U}.
{2}{U}: Put an hour counter on this artifact.
At the beginning of each upkeep, put an hour counter on this artifact.
When the twelfth hour counter is put on this artifact, shuffle your hand and graveyard into your library, then draw seven cards. Exile this artifact.

Chill of Foreboding

Each player mills five cards.
Flashback {7}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Call of the Nightwing

Create a 1/1 blue and black Horror creature token with flying.
Cipher (Then you may exile this spell card encoded on a creature you control. Whenever that creature deals combat damage to a player, its controller may cast a copy of the encoded card without paying its mana cost.)

River of Tears

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

Dread Summons

Each player mills X cards. For each creature card put into a graveyard this way, you create a tapped 2/2 black Zombie creature token. (To mill a card, a player puts the top card of their library into their graveyard.)

Psychic Drain

Target player mills X cards and you gain X life.

Scavenger Grounds

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

Castle Vantress

This land enters tapped unless you control an Island.
{T}: Add {U}.
{2}{U}{U}, {T}: Scry 2.

Didn't Say Please

Counter target spell. Its controller mills three cards.

Darkwater Catacombs

Island

Cut Your Losses

Casualty 2 (As you cast this spell, you may sacrifice a creature with power 2 or greater. When you do, copy this spell and you may choose a new target for the copy.)
Target player mills half their library, rounded down.

Tormod's Crypt

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

Dimir Aqueduct

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

Misery's Shadow

If a creature an opponent controls would die, exile it instead.
{1}: This creature gets +1/+1 until end of turn.

Stone of Erech

If a creature an opponent controls would die, exile it instead.
{2}, {T}, Sacrifice Stone of Erech: Exile target player's graveyard. Draw a card.

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.

Fascination

Choose one —
• Each player draws X cards.
• Each player mills X cards.

Compelling Argument

Target player mills five cards.
Cycling {U} ({U}, Discard this card: Draw a card.)

Dismal Backwater

Dissipate

Counter target spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

Blot Out

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

Can't Wake Up

Target player mills four cards. (Then exile this card. You may cast the creature later from exile.)

Cruel Somnophage

Cruel Somnophage's power and toughness are each equal to the number of creature cards in all graveyards.

Cruel Somnophage // Can't Wake Up

Falthis, Shadowcat Familiar

Commanders you control have menace and deathtouch.
Partner (You can have two commanders if both have partner.)

Codex Shredder

{T}: Target player mills a card. (They put the top card of their library into their graveyard.)
{5}, {T}, Sacrifice this artifact: Return target card from your graveyard to your hand.

Dimir Signet

Call to Mind

Pull from the Deep

Return up to one target instant card and up to one target sorcery card from your graveyard to your hand. Exile Pull from the Deep.

Nephalia Drownyard

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

Dreadwaters

Target player mills X cards, where X is the number of lands you control.

Scry 1. (Look at the top card of your library. You may put that card on the bottom.)
Draw a card.

Psionic Ritual

Replicate—Tap an untapped Horror you control. (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)
Exile target instant or sorcery card from a graveyard and copy it. You may cast the copy without paying its mana cost.
Exile Psionic Ritual.

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.

Contaminated Aquifer

({T}: Add {U} or {B}.)
This land enters tapped.

Forgotten Creation

Skulk (This creature can't be blocked by creatures with greater power.)
At the beginning of your upkeep, you may discard all the cards in your hand. If you do, draw that many cards.

Awoken Horror

When this creature transforms into Awoken Horror, return all non-Horror creatures to their owners' hands.

Thing in the Ice

Defender
This creature enters with four ice counters on it.
Whenever you cast an instant or sorcery spell, remove an ice counter from this creature. Then if it has no ice counters on it, transform it.

Thing in the Ice // Awoken Horror

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.

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.

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)