Millikin

{T}, Mill a card: Add {C}. (To mill a card, put the top card of your library into your graveyard.)

Restless Reef

This land enters tapped.
{T}: Add {U} or {B}.
{2}{U}{B}: Until end of turn, this land becomes a 4/4 blue and black Shark creature with deathtouch. It's still a land.
Whenever this land attacks, target player mills four cards.

Unhallowed Phalanx

Fleet Swallower

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

Submerged Boneyard

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

Drowned Catacomb

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

Dark Ritual

Silent Arbiter

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

Command Tower

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

Jace, Wielder of Mysteries

If you would draw a card while your library has no cards in it, you win the game instead.
+1: Target player mills two cards. Draw a card.
−8: Draw seven cards. Then if your library has no cards in it, you win the game.

Sire of Stagnation

Devoid (This card has no color.)
Whenever a land an opponent controls enters, that player exiles the top two cards of their library and you draw two cards.

Sunken Ruins

{T}: Add {C}.
{U/B}, {T}: Add {U}{U}, {U}{B}, or {B}{B}.

Hover Barrier

Hydroelectric Laboratory

As this land enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {U}.

Hydroelectric Specimen

Flash
When this creature enters, you may change the target of target instant or sorcery spell with a single target to this creature.

Hydroelectric Specimen // Hydroelectric Laboratory

Can't Wake Up

Target player mills four cards. (Then exile this card. You may cast the creature later from exile.)

Cruel Somnophage

Cruel Somnophage's power and toughness are each equal to the number of creature cards in all graveyards.

Cruel Somnophage // Can't Wake Up

Island

Wall of Runes

Defender (This creature can't attack.)
When this creature enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

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.)

The Ancient One

Descend 8 — The Ancient One can't attack or block unless there are eight or more permanent cards in your graveyard.
{2}{U}{B}: Draw a card, then discard a card. When you discard a card this way, target player mills cards equal to its 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.

Wall of Junk

Defender (This creature can't attack.)
When this creature blocks, return it to its owner's hand at end of combat. (Return it only if it's on the battlefield.)

Mortal Combat

At the beginning of your upkeep, if twenty or more creature cards are in your graveyard, you win the game.

Darkslick Shores

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

Venture Deeper

Merfolk Secretkeeper

Merfolk Secretkeeper // Venture Deeper

Hagra Broodpit

Hagra Mauling

This spell costs {1} less to cast if an opponent controls no basic lands.
Destroy target creature.

Hagra Mauling // Hagra Broodpit

Undercity Sewers

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

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.)

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.)

Visions of Beyond

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

Dreamborn Muse

At the beginning of each player's upkeep, that player mills X cards, where X is the number of cards in their hand.

Sol Ring

Fell Mire

As this land enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {B}.

Fell the Profane

Fell the Profane // Fell Mire

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."

Fellwar Stone

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

Murkwater Pathway

Clearwater Pathway

Clearwater Pathway // Murkwater Pathway

Didn't Say Please

Counter target spell. Its controller mills three cards.

Morphic Pool

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

Swamp

Nighthowler

Bestow {2}{B}{B} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)
This creature and enchanted creature each get +X/+X, where X is the number of creature cards in all graveyards.

Glacial Wall

Caelorna, Coral Tyrant

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}.

Laboratory Maniac

If you would draw a card while your library has no cards in it, you win the game instead.

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.

Aegis Turtle

Wall of Mist

Ioreth of the Healing House

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

Eater of the Dead

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

Deranged Assistant

Mortivore

Mortivore's power and toughness are each equal to the number of creature cards in all graveyards.
{B}: Regenerate this creature. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

King Macar, the Gold-Cursed

Inspired — Whenever King Macar becomes untapped, you may exile target creature. If you do, create a Gold token. (It's an artifact with "Sacrifice this token: Add one mana of any color.")

Tree of Perdition

Defender
{T}: Exchange target opponent's life total with this creature's toughness.

Traumatize

Target player mills half their library, rounded down.

Dimir Aqueduct

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

Wall of Frost

Defender
Whenever this creature blocks a creature, that creature doesn't untap during its controller's next untap step.

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.)

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.)

Doomsday

Search your library and graveyard for five cards and exile the rest. Put the chosen cards on top of your library in any order. You lose half your life, rounded up.

Dramatic Reversal

Untap all nonland permanents you control.

Crashing Drawbridge

Defender
{T}: Creatures you control gain haste until end of turn.

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.

Thassa's Oracle

When this creature enters, look at the top X cards of your library, where X is your devotion to blue. Put up to one of them on top of your library and the rest on the bottom of your library in a random order. If X is greater than or equal to the number of cards in your library, you win the game. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)

Manakin

Tainted Isle

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

Corrupted Shapeshifter

Devoid (This card has no color.)
As this creature enters, it becomes your choice of a 3/3 creature with flying, a 2/5 creature with vigilance, or a 0/12 creature with defender.