Commander's Sphere

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

Treno, Dark City

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

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.

Thought Vessel

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

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.)

Carrion Locust

Flying
When this creature enters, exile target card from an opponent's graveyard. If it was a creature card, that player loses 1 life.

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.)

Swamp

Sign in Blood

Target player draws two cards and loses 2 life.

Dauthi Horror

Shadow (This creature can block or be blocked by only creatures with shadow.)
This creature can't be blocked by white creatures.

Risky Shortcut

Draw two cards. Each player loses 2 life.

Dimir Aqueduct

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

Stitched Mangler

This creature enters tapped.
When this creature enters, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.

Deadly Dispute

As an additional cost to cast this spell, sacrifice an artifact or creature.
Draw two cards and create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Syr Konrad, the Grim

Whenever another creature dies, or a creature card is put into a graveyard from anywhere other than the battlefield, or a creature card leaves your graveyard, Syr Konrad deals 1 damage to each opponent.
{1}{B}: Each player mills a card. (They each put the top card of their library into their graveyard.)

Toxrill, the Corrosive

At the beginning of each end step, put a slime counter on each creature you don't control.
Creatures you don't control get -1/-1 for each slime counter on them.
Whenever a creature you don't control with a slime counter on it dies, create a 1/1 black Slug creature token.
{U}{B}, Sacrifice a Slug: Draw a card.

Command Tower

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

Waterfront District

This land enters tapped.
{T}: Add {U} or {B}.
{2}{U}{B}, {T}, Sacrifice this land: Draw a card.

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.

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.

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.

Phenomenon Investigators

As this creature enters, choose Believe or Doubt.
• Believe — Whenever a nontoken creature you control dies, create a 2/2 black Horror enchantment creature token.
• Doubt — At the beginning of your end step, you may return a nonland permanent you own to your hand. If you do, draw a card.

Solemn Simulacrum

When this creature enters, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When this creature dies, you may draw a card.

Tonberry

This creature enters tapped with a stun counter on it. (If it would become untapped, remove a stun counter from it instead.)
Chef's Knife — During your turn, this creature has first strike and deathtouch.

Phyrexian Obliterator

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

Vibrant Cityscape

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

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.

Island

Diabolic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Frantic Search

Draw two cards, then discard two cards. Untap up to three lands.

Arcane Signet

Horrid Shadowspinner

Lifelink
Whenever this creature attacks, you may draw cards equal to its power. If you do, discard that many cards.

Dragonstorm Globe

Each Dragon you control enters with an additional +1/+1 counter on it.
{T}: Add one mana of any color.

Sewer Nemesis

As this creature 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.

Nemesis of Reason

Whenever this creature attacks, defending player mills ten cards.

Perfected Form

Aberrant Researcher

Flying
At the beginning of your upkeep, mill a card. If an instant or sorcery card was milled this way, transform this creature. (To mill a card, put the top card of your library into your graveyard.)

Aberrant Researcher // Perfected Form

Guiltfeeder

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

Doomsday Excruciator

Flying
When this creature enters, if it was cast, each player exiles all but the bottom six cards of their library face down.
At the beginning of your upkeep, draw a card.

The Water Crystal

Blue spells you cast cost {1} less to cast.
If an opponent would mill one or more cards, they mill that many cards plus four instead.
{4}{U}{U}, {T}: Each opponent mills cards equal to the number of cards in your hand.

Defabricate

Choose one —
• Counter target artifact or enchantment spell. If a spell is countered this way, exile it instead of putting it into its owner's graveyard.
• Counter target activated or triggered ability.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice this artifact: Draw a card.

Rogue's Passage

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

Dunland Crebain

Flying
When this creature enters, amass Orcs 2. (Put two +1/+1 counters on an Army you control. It's also an Orc. If you don't control an Army, create a 0/0 black Orc Army creature token first.)

Negate

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.")

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.

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.)

Dismal Backwater

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

Ahriman

Flying, deathtouch
{3}, Sacrifice another creature or artifact: Draw a card.

Sol Ring

Insatiable Skittermaw

Menace (This creature can't be blocked except by two or more creatures.)
Void — At the beginning of your end step, if a nonland permanent left the battlefield this turn or a spell was warped this turn, put a +1/+1 counter on this creature.

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

Breach the Multiverse

Each player mills ten cards. For each player, choose a creature or planeswalker card in that player's graveyard. Put those cards onto the battlefield under your control. Then each creature you control becomes a Phyrexian in addition to its other types.

Grell Philosopher

Aberrant Tinkering — When this creature 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.

Raise the Palisade

Choose a creature type. Return all creatures that aren't of the chosen type to their owners' hands.

Mindcrank

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

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.

Evolving Wilds

Hedron Crab

Landfall — Whenever a land you control enters, target player mills three cards. (They put the top three cards of their library into their graveyard.)

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.

Bident of Thassa

Whenever a creature you control deals combat damage to a player, you may draw a card.
{1}{U}, {T}: Creatures your opponents control attack this turn if able.

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.

Hymn of the Faller

Surveil 1, then you draw a card and lose 1 life. (To surveil 1, look at the top card of your library. You may put it into your graveyard.)
Void — If a nonland permanent left the battlefield this turn or a spell was warped this turn, draw another card.

Stern Lesson

Draw two cards, then discard a card. Create a tapped Powerstone token. (It's an artifact with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")

Sinister Hideout

This land enters tapped.
{T}: Add {U} or {B}.
{4}, {T}: Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Singularity Rupture

Destroy all creatures, then any number of target players each mill half their library, rounded down.

Village Rites

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

Imprisoned in the Moon

Enchant creature, land, or planeswalker
Enchanted permanent is a colorless land with "{T}: Add {C}" and loses all other card types and abilities.

Qutrub Forayer

When this creature enters, choose one —
• Destroy target creature that was dealt damage this turn.
• Exile up to two target cards from a single graveyard.

Spectral Interference

Counter target artifact or creature spell unless its controller pays {4}.

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.