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 greater.

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.)

Psychic Corrosion

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

Psychic Strike

Counter target spell. Its controller mills two cards.

Mistvault Bridge

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

Counterspell

Grim Tutor

Search your library for a card, put that card into your hand, then shuffle. You lose 3 life.

Wall of Lost Thoughts

Defender (This creature can't attack.)
When this creature enters, target player mills four cards. (They put the top four cards of their library into their graveyard.)

Thought Collapse

Counter target spell. Its controller mills three cards.

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.)

Negate

Commander's Sphere

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

Unstoppable Plan

At the beginning of your end step, untap all nonland permanents you control.

Perplex

Counter target spell unless its controller discards their hand.
Transmute {1}{U}{B} ({1}{U}{B}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

Island

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.

Mindcrank

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

Charix, the Raging Isle

Spells your opponents cast that target Charix cost {2} more to cast.
{3}: Charix gets +X/-X until end of turn, where X is the number of Islands you control.

Watery Grave

({T}: Add {U} or {B}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Altar of the Brood

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

Thought Scour

Target player mills two cards.
Draw a card.

Ioreth of the Healing House

{T}: Untap another target permanent.
{T}: Untap two other target legendary creatures.

Morphic Pool

This land enters tapped unless you have two or more opponents.
{T}: Add {U} or {B}.

The Walls of Ba Sing Se

Defender
Other permanents you control have indestructible.

Omni-Changeling

Changeling (This card is every creature type.)
Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
You may have this creature enter as a copy of any creature on the battlefield, except it has changeling.

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}.

Mana Drain

Counter target spell. At the beginning of your next main phase, add an amount of {C} equal to that spell's mana value.

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.

Maddening Cacophony

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

Traumatize

Target player mills half their library, rounded down.

Propaganda

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Mesmeric Orb

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

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.)

Arcane Signet

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

Swamp

Visions of Beyond

Draw a card. If a graveyard has twenty or more cards in it, draw three cards instead.

Kitsune's Technique

Sneak {1}{U} (You may cast this spell for {1}{U} if you also return an unblocked attacker you control to hand during the declare blockers step.)
Target opponent mills half their library, rounded up.

Thousand-Year Elixir

You may activate abilities of creatures you control as though those creatures had haste.
{1}, {T}: Untap target creature.

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

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.

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.)

Dimir Aqueduct

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

Shipwreck Marsh

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

Nephalia Drownyard

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

Eater of the Dead

{0}: If this creature is tapped, exile target creature card from a graveyard and untap this creature.

Demonic Tutor

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

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.)

Dimir Guildgate

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

Inundated Archive

Waterlogged Teachings

Search your library for an instant card or a card with flash, reveal it, put it into your hand, then shuffle.

Waterlogged Teachings // Inundated Archive

Silent Arbiter

No more than one creature can attack each combat.
No more than one creature can block each combat.

Fellwar Stone

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

Dramatic Reversal

Untap all nonland permanents you control.

Fetid Pools

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

Riverchurn Monument

{1}, {T}: Any number of target players each mill two cards. (Each of them puts the top two cards of their library into their graveyard.)
Exhaust — {2}{U}{U}, {T}: Any number of target players each mill cards equal to the number of cards in their graveyard. (Activate each exhaust ability only once.)

Memory Erosion

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

Nemesis of Reason

Whenever this creature attacks, defending player mills ten cards.

Darkslick Shores

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

Underground Sea

Diabolic Tutor

Freed from the Real

Enchant creature
{U}: Tap enchanted creature.
{U}: Untap enchanted creature.

Contaminated Aquifer

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

Duskmantle Guildmage

{1}{U}{B}: Whenever a card is put into an opponent's graveyard from anywhere this turn, that player loses 1 life.
{2}{U}{B}: Target player mills two cards.

Phenax, God of Deception

Indestructible
As long as your devotion to blue and black is less than seven, Phenax isn't a creature.
Creatures you control have "{T}: Target player mills X cards, where X is this creature's toughness."

Consecrated Sphinx

Flying
Whenever an opponent draws a card, you may draw two cards.

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.)

Command Tower

Bonehoard

Living weapon (When this Equipment enters, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)
Equipped creature gets +X/+X, where X is the number of creature cards in all graveyards.
Equip {2}

Imperial Seal

Search your library for a card, then shuffle and put that card on top. You lose 2 life.

Dark Ritual

Wight of Precinct Six

This creature gets +1/+1 for each creature card in your opponents' graveyards.

Intruder Alarm

Creatures don't untap during their controllers' untap steps.
Whenever a creature enters, untap all creatures.

Dismal Backwater

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

Hover Barrier

Frost Marsh

Opposition Agent

Flash
You control your opponents while they're searching their libraries.
While an opponent is searching their library, they exile each card they find. You may play those cards for as long as they remain exiled, and you may spend mana as though it were mana of any color to cast them.

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.

Singularity Rupture

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

Profane Memento

Whenever a creature card is put into an opponent's graveyard from anywhere, you gain 1 life.

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.