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.

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.)

Dimir Guildgate

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

Campfire

{1}, {T}: You gain 2 life.
{2}, {T}, Exile this artifact: Put all commanders you own from the command zone and from your graveyard into your hand. Then shuffle your graveyard into your library.

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.

Necropolis Regent

Flying
Whenever a creature you control deals combat damage to a player, put that many +1/+1 counters on it.

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.

Memory Deluge

Look at the top X cards of your library, where X is the amount of mana spent to cast this spell. Put two of them into your hand and the rest on the bottom of your library in a random order.
Flashback {5}{U}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Charcoal Diamond

This artifact enters tapped.
{T}: Add {B}.

Mesmeric Orb

Whenever a permanent becomes untapped, that permanent's controller mills a card.

Unseal the Necropolis

Each player mills three cards. Then you return up to two creature cards from your graveyard to your hand. (To mill three cards, a player puts the top three cards of their library into their graveyard.)

Island

Talisman of Dominance

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

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.)

Sky Diamond

This artifact enters tapped.
{T}: Add {U}.

Frightcrawler

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
Threshold — As long as seven or more cards are in your graveyard, this creature gets +2/+2 and can't block.

Ravenous Chupacabra

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

Dimir Aqueduct

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

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}.

Vizier of Many Faces

You may have this creature enter as a copy of any creature on the battlefield, except if this creature was embalmed, the token has no mana cost, it's white, and it's a Zombie in addition to its other types.
Embalm {3}{U}{U}

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.

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.

Rogue's Passage

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

Mystical Tutor

Search your library for an instant or sorcery card, reveal it, then shuffle and put that card on top.

Navigation Orb

{2}, {T}, Sacrifice this artifact: Search your library for up to two basic land cards and/or Gate cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Bojuka Bog

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

Tainted Isle

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

Drowned Catacomb

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

Mask of Griselbrand

Equipped creature has flying and lifelink.
Whenever equipped creature dies, you may pay X life, where X is its power. If you do, draw X cards.
Equip {3}

Feed the Swarm

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

Childhood Horror

Flying
Threshold — As long as seven or more cards are in your graveyard, this creature gets +2/+2 and can't block.

Shipwreck Marsh

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

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.

Overcharged Amalgam

Flash
Flying
Exploit (When this creature enters, you may sacrifice a creature.)
When this creature exploits a creature, counter target spell, activated ability, or triggered ability.

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.

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.

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.

Changeling Outcast

Changeling (This card is every creature type.)
This creature can't block and can't be blocked.

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.)

Phyrexian Arena

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

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.

Irenicus's Vile Duplication

Create a token that's a copy of target creature you control, except the token has flying and it isn't legendary.

Syphon Mind

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

Realmbreaker, the Invasion Tree

{2}, {T}: Target opponent mills three cards. Put a land card from their graveyard onto the battlefield tapped under your control. It gains "If this land would leave the battlefield, exile it instead of putting it anywhere else."
{10}, {T}, Sacrifice Realmbreaker: Search your library for any number of Praetor cards, put them onto the battlefield, then shuffle.

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.

Dauthi Horror

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

Command Tower

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

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.

Underground River

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

Dark Ritual

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.)

Dread Return

Return target creature card from your graveyard to the battlefield.
Flashback—Sacrifice three creatures. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Arcane Adaptation

As this enchantment enters, choose a creature type.
Creatures you control are the chosen type in addition to their other types. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.

Counterspell

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.

Windfall

Each player discards their hand, then draws cards equal to the greatest number of cards a player discarded this way.

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.

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.)

Disdainful Stroke

Counter target spell with mana value 4 or greater.

Contaminated Aquifer

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

Siphon Insight

Look at the top two cards of target opponent's library. Exile one of them face down and put the other on the bottom of that library. You may play the exiled card for as long as it remains exiled, and you may spend mana as though it were mana of any color to cast that spell.
Flashback {1}{U}{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.

Lazotep Convert

You may have Lazotep Convert enter as a copy of any creature card in a graveyard, except it's a 4/4 black Zombie in addition to its other colors and types.

Invasion of Amonkhet

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When Invasion of Amonkhet enters, each player mills three cards, then each opponent discards a card and you draw a card. (To mill three cards, a player puts the top three cards of their library into their graveyard.)

Invasion of Amonkhet // Lazotep Convert

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.

Neurok Stealthsuit

Equipped creature has shroud. (It can't be the target of spells or abilities.)
{U}{U}: Attach Neurok Stealthsuit to target creature you control.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Pull from Tomorrow

Arcane Signet

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 Cruelty of Gix

Read ahead (Choose a chapter and start with that many lore counters. Add one after your draw step. Skipped chapters don't trigger. Sacrifice after III.)
I — Target opponent reveals their hand. You choose a creature or planeswalker card from it. That player discards that card.
II — Search your library for a card, put that card into your hand, then shuffle. You lose 3 life.
III — Put target creature card from a graveyard onto the battlefield under your control.

Hunted Horror

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

Everflowing Chalice

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

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.

Memory Plunder

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

Cling to Dust

Exile target card from a graveyard. If it was a creature card, you gain 3 life. Otherwise, you draw a card.
Escape—{3}{B}, Exile five other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)

Sol Ring

Demolition Field

{T}: Add {C}.
{2}, {T}, Sacrifice this land: Destroy target nonbasic land an opponent controls. That land's controller may search their library for a basic land card, put it onto the battlefield, then shuffle. You may search your library for a basic land card, put it onto the battlefield, then shuffle.

Mindcrank

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

Sunken Hollow

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