Everflowing Chalice

Multikicker {2} (You may pay an additional {2} any number of times as you cast this spell.)
Everflowing Chalice enters with a charge counter on it for each time it was kicked.
{T}: Add {C} for each charge counter on Everflowing Chalice.

Mystic Sanctuary

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

Nephalia Drownyard

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

Psychic Corrosion

Whenever you draw a card, each opponent mills two cards.

Creeping Tar Pit

Creeping Tar Pit enters tapped.
{T}: Add {U} or {B}.
{1}{U}{B}: Creeping Tar Pit becomes a 3/2 blue and black Elemental creature until end of turn and can't be blocked this turn. It's still a land.

Sphinx's Tutelage

Whenever you draw a card, target opponent mills two cards. If two nonland cards that share a color were milled this way, repeat this process.
{5}{U}: Draw a card, then discard a card.

Hunted Horror

Trample
When Hunted Horror enters, target opponent creates two 3/3 green Centaur creature tokens with protection from black.

Phyrexian Rager

When Phyrexian Rager enters, you draw a card and you lose 1 life.

Drownyard Temple

{T}: Add {C}.
{3}: Return Drownyard Temple from your graveyard to the battlefield tapped.

Umbris, Fear Manifest

Umbris, Fear Manifest 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.

Maddening Cacophony

Kicker {3}{U}
Each opponent mills eight cards. If this spell was kicked, instead each opponent mills half their library, rounded up.

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.

Psychic Strike

Counter target spell. Its controller mills two cards.

Swamp

Arcane Signet

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

Hullbreaker Horror

Flash
This spell can't be countered.
Whenever you cast a spell, choose up to one —
• Return target spell you don't control to its owner's hand.
• Return target nonland permanent to its owner's hand.

Dimir Signet

Talisman of Dominance

{T}: Add {C}.
{T}: Add {U} or {B}. Talisman of Dominance deals 1 damage to you.

Exotic Orchard

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

Negate

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.

Hostage Taker

When Hostage Taker enters, exile another target creature or artifact until Hostage Taker leaves the battlefield. You may cast that card for as long as it remains exiled, and mana of any type can be spent to cast that spell.

Wrexial, the Risen Deep

Islandwalk, swampwalk (This creature can't be blocked as long as defending player controls an Island or a Swamp.)
Whenever Wrexial, the Risen Deep deals combat damage to a player, you may cast target instant or sorcery card from that player's graveyard without paying its mana cost. If that spell would be put into a graveyard, exile it instead.

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 Endless Evil to its owner's hand.

Spellskite

{U/P}: Change a target of target spell or ability to Spellskite. ({U/P} can be paid with either {U} or 2 life.)

Pull from Tomorrow

Memory Erosion

Whenever an opponent casts a spell, that player mills two cards.

Path of Ancestry

Path of Ancestry 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.)

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}.

Bruvac the Grandiloquent

If an opponent would mill one or more cards, they mill twice that many cards instead. (To mill a card, a player puts the top card of their library into their graveyard.)

River of Tears

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

Island

Shadow Kin

Flash
At the beginning of your upkeep, each player mills three cards. You may exile a creature card from among the cards milled this way. If you do, Shadow Kin becomes a copy of that card, except it has this ability.

Dimir Aqueduct

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

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.

Mindcrank

Whenever an opponent loses life, that player mills that many cards. (Damage causes loss of life.)

Sewer Nemesis

As Sewer Nemesis enters, choose a player.
Sewer Nemesis's power and toughness are each equal to the number of cards in the chosen player's graveyard.
Whenever the chosen player casts a spell, that player mills a card.

Fabled Passage

{T}, Sacrifice Fabled Passage: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Then if you control four or more lands, untap that land.

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.

Ash Barrens

{T}: Add {C}.
Basic landcycling {1} ({1}, Discard this card: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.)

Tainted Isle

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

Port of Karfell

Port of Karfell enters tapped.
{T}: Add {U}.
{3}{U}{B}{B}, {T}, Sacrifice Port of Karfell: 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.)

Extract from Darkness

Each player mills two cards. Then you put a creature card from a graveyard onto the battlefield under your control.

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.)

Altar of the Brood

Whenever another permanent you control enters, each opponent mills a card.

Crippling Fear

Choose a creature type. Creatures that aren't of the chosen type get -3/-3 until end of turn.

Shipwreck Marsh

Shipwreck Marsh enters tapped unless you control two or more other lands.
{T}: Add {U} or {B}.

Haunted One

Commander creatures you own have "Whenever this creature becomes tapped, it and other creatures you control that share a creature type with it each get +2/+0 and gain undying until end of turn." (When a creature with undying dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

Feed the Swarm

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

Ravenous Chupacabra

When Ravenous Chupacabra enters, destroy target creature an opponent controls.

Commander's Sphere

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

Arvinox, the Mind Flail

Arvinox, the Mind Flail isn't a creature unless you control three or more permanents you don't own.
At the beginning of your end step, exile the bottom card of each opponent's library face down. For as long as those cards remain exiled, you may look at them, you may cast permanent spells from among them, and you may spend mana as though it were mana of any color to cast those spells.

Choked Estuary

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

Fellwar Stone

Mind Stone

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

Fetid Pools

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

Castle Vantress

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

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Fractured Sanity

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

Mind Grind

Each opponent reveals cards from the top of their library until they reveal X land cards, then puts all cards revealed this way into their graveyard. X can't be 0.

Command Tower

Darkwater Catacombs

Sludge Monster

Whenever Sludge Monster 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.

Fact or Fiction

Reveal the top five cards of your library. An opponent separates those cards into two piles. Put one pile into your hand and the other into your graveyard.

Thief of Sanity

Flying
Whenever Thief of Sanity deals combat damage to a player, look at the top three cards of that player's library, exile one of them face down, then put the rest into their graveyard. You may cast that card for as long as it remains exiled, and mana of any type can be spent to cast that spell.

Memory Plunder

You may cast target instant or sorcery card from an opponent's graveyard without paying its mana cost.

Phyrexian Revoker

As Phyrexian Revoker enters, choose a nonland card name.
Activated abilities of sources with the chosen name can't be activated.

Sol Ring

Drown in the Loch

Choose one —
• Counter target spell with mana value less than or equal to the number of cards in its controller's graveyard.
• Destroy target creature with mana value less than or equal to the number of cards in its controller's graveyard.

Aboleth Spawn

Flash
Ward {2}
Probing Telepathy — Whenever a creature entering under an opponent's control causes a triggered ability of that creature to trigger, you may copy that ability. You may choose new targets for the copy.

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.

Counterspell

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.

Grell Philosopher

Aberrant Tinkering — When Grell Philosopher enters and at the beginning of your upkeep, each Horror you control gains all activated abilities of target artifact an opponent controls until end of turn. You may spend blue mana as though it were mana of any color to activate those abilities.

Sunken Hollow

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

Infernal Grasp

Destroy target creature. You lose 2 life.

Brainstealer Dragon

Flying
At the beginning of your end step, exile the top card of each opponent's library. You may play those 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.
Whenever a nonland permanent an opponent owns enters the battlefield under your control, they lose life equal to its mana value.

Drowned Secrets

Whenever you cast a blue spell, target player mills two cards.

Baleful Mastery

You may pay {1}{B} rather than pay this spell's mana cost.
If the {1}{B} cost was paid, an opponent draws a card.
Exile target creature or planeswalker.

Nemesis of Reason

Whenever Nemesis of Reason attacks, defending player mills ten cards.

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 Uchuulon.

Ruin Crab

Landfall — Whenever a land you control enters, each opponent mills three cards. (To mill a card, a player puts the top card of their library into their graveyard.)

Guiltfeeder

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
Whenever Guiltfeeder attacks and isn't blocked, defending player loses 1 life for each card in their graveyard.

Maskwood Nexus

Creatures you control are every creature type. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.
{3}, {T}: Create a 2/2 blue Shapeshifter creature token with changeling. (It is every creature type.)

Court of Cunning

When Court of Cunning 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.)

Cunning Evasion

Whenever a creature you control becomes blocked, you may return it to its owner's hand.

In Garruk's Wake

Destroy all creatures you don't control and all planeswalkers you don't control.

Glasspool Shore

Glasspool Shore enters tapped.
{T}: Add {U}.

Glasspool Mimic

You may have Glasspool Mimic enter as a copy of a creature you control, except it's a Shapeshifter Rogue in addition to its other types.

Glasspool Mimic // Glasspool Shore

Mind Flayer

Dominate Monster — When Mind Flayer enters, gain control of target creature for as long as you control Mind Flayer.

An Offer You Can't Refuse

Counter target noncreature spell. Its controller creates two Treasure tokens. (They're artifacts with "{T}, Sacrifice this token: Add one mana of any color.")