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.)

Command Tower

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

Paranoid Delusions

Target player mills three cards.
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.)

Thought Scour

Target player mills two cards.
Draw a card.

Glimpse the Unthinkable

Maddening Cacophony

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

Nemesis of Reason

Whenever this creature attacks, defending player mills ten cards.

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.

Traumatize

Target player mills half their library, rounded down.

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.

Windfall

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

Mirko Vosk, Mind Drinker

Flying
Whenever Mirko Vosk deals combat damage to a player, that player reveals cards from the top of their library until they reveal four land cards, then puts those cards into their graveyard.

Reliquary Tower

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

Mind Funeral

Target opponent reveals cards from the top of their library until four land cards are revealed. That player puts all cards revealed this way into their graveyard.

Bojuka Bog

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

Dimir Doppelganger

{1}{U}{B}: Exile target creature card from a graveyard. This creature becomes a copy of that card, except it has this ability.

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.)

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.)

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.

Island

Teferi's Tutelage

When this enchantment enters, draw a card, then discard a card.
Whenever you draw a card, target opponent mills two cards. (They put the top two cards of their library into their graveyard.)

Extract from Darkness

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

Mind Sculpt

Swamp

Memory Erosion

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

Sol Ring

Didn't Say Please

Counter target spell. Its controller mills three cards.

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.)

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.

Propaganda

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

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.

Terisian Mindbreaker

Whenever this creature attacks, defending player mills half their library, rounded up.
Unearth {1}{U}{U}{U} ({1}{U}{U}{U}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

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.)

Mindcrank

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

Reanimate

Put target creature card from a graveyard onto the battlefield under your control. You lose life equal to that card's mana value.

Notion Thief

Flash
If an opponent would draw a card except the first one they draw in each of their draw steps, instead that player skips that draw and you draw a card.

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.)

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.

Persistent Petitioners

{1}, {T}: Target player mills a card. (They put the top card of their library into their graveyard.)
Tap four untapped Advisors you control: Target player mills twelve cards.
A deck can have any number of cards named Persistent Petitioners.

Psychic Corrosion

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

Grisly Spectacle

Destroy target nonartifact creature. Its controller mills cards equal to that creature's power.

Rise of the Dark Realms

Put all creature cards from all graveyards onto the battlefield under your control.

Visions of Beyond

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

Arcane Signet

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.)

Lazav, Dimir Mastermind

Hexproof
Whenever a creature card is put into an opponent's graveyard from anywhere, you may have Lazav become a copy of that card, except its name is Lazav, Dimir Mastermind, it's legendary in addition to its other types, and it has hexproof and this ability.

Psychic Strike

Counter target spell. Its controller mills two 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.

Thought Vessel

Fleet Swallower

Whenever this creature attacks, target player mills half their library, rounded up.

Sword of Body and Mind

Equipped creature gets +2/+2 and has protection from green and from blue.
Whenever equipped creature deals combat damage to a player, you create a 2/2 green Wolf creature token and that player mills ten cards.
Equip {2}

Memory Plunder

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

Mesmeric Orb

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

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, this creature becomes a copy of that card, except it has this ability.

Crypt Incursion

Exile all creature cards from target player's graveyard. You gain 3 life for each card exiled this way.

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.

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.

Singularity Rupture

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