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.

Mystic Sanctuary

({T}: Add {U}.)
This land enters tapped unless you control three or more other Islands.
When this land enters untapped, you may put target instant or sorcery card from your graveyard on top of your library.

Sign in Blood

Target player draws two cards and loses 2 life.

Aetherize

Return all attacking creatures to their owner's hand.

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.

Nephalia Drownyard

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

Thought Collapse

Counter target spell. Its controller mills three cards.

Infernal Grasp

Destroy target creature. You lose 2 life.

Overture

Target opponent mills half their library, rounded down. (Then exile this card. You may play the land later from exile.)

Jidoor, Aristocratic Capital

Jidoor, Aristocratic Capital // Overture

Swamp

Dark Deal

Each player discards all the cards in their hand, then draws that many cards minus one.

Novijen Sages

Graft 4 (This creature enters with four +1/+1 counters on it. Whenever another creature enters, you may move a +1/+1 counter from this creature onto it.)
{1}, Remove two +1/+1 counters from among creatures you control: Draw a card.

Whispering Madness

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

Lo and Li, Royal Advisors

Whenever an opponent discards a card or mills one or more cards, put a +1/+1 counter on each Advisor you control.
{2}{U/B}: Target player mills four cards. (They put the top four cards of their library into their graveyard.)

Propaganda

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

Sol Ring

Command Tower

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

Secluded Courtyard

As this land enters, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type or activate an ability of a creature source of the chosen type.

Withering Torment

Destroy target creature or enchantment. You lose 2 life.

Memory Plunder

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

Island

Ripples of Potential

Proliferate, then choose any number of permanents you control that had a counter put on them this way. Those permanents phase out. (To proliferate, choose any number of permanents and/or players, then give each another counter of each kind already there. Treat phased-out permanents and anything attached to them as though they don't exist until their controller's next turn.)

Intruder Alarm

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

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.

Night's Whisper

Counterspell

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.

Riddlekeeper

Whenever a creature attacks you or a planeswalker you control, that creature's controller mills two cards.

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.

Thought Vessel

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

Duskmantle, House of Shadow

{T}: Add {C}.
{U}{B}, {T}: Target player mills a card.

Feed the Swarm

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

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.

Danny Pink

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Creatures you control have "Whenever one or more counters are put on this creature for the first time each turn, draw a card."

Tainted Isle

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

Echoing Return

Return target creature card and all other cards with the same name as that card from your graveyard to your hand.

Sunken Hollow

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

Wave Goodbye

Return each creature without a +1/+1 counter on it to its owner's hand.

Grindstone

{3}, {T}: Target player mills two cards. If two cards that share a color were milled this way, repeat this process.

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.)

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}.

Toxic Deluge

As an additional cost to cast this spell, pay X life.
All creatures get -X/-X until end of turn.

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.)

Mass Appeal

Pongify

Destroy target creature. It can't be regenerated. Its controller creates a 3/3 green Ape creature token.

Glimpse the Unthinkable

Drowned Catacomb

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

Psychic Strike

Counter target spell. Its controller mills two cards.

Oppression

Whenever a player casts a spell, that player discards a card.

Deepmuck Desperado

Whenever you commit a crime, each opponent mills three cards. This ability triggers only once each turn. (Targeting opponents, anything they control, and/or cards in their graveyards is a crime.)

Underground River

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

Duelist of the Mind

Flying, vigilance
Duelist of the Mind's power is equal to the number of cards you've drawn this turn.
Whenever you commit a crime, you may draw a card. If you do, discard a card. This ability triggers only once each turn.

Talisman of Dominance

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

Extract from Darkness

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

Siren of the Silent Song

Flying
Inspired — Whenever this creature becomes untapped, each opponent discards a card, then each opponent mills a card.

Training Grounds

Activated abilities of creatures you control cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.

Unstoppable Plan

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

Didn't Say Please

Cunning Advisor

{T}: Target opponent discards a card. Activate only during your turn, before attackers are declared.

Arcane Signet

Reliquary Tower

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.)

Drowned Secrets

Whenever you cast a blue spell, target player mills two cards.

Path of Ancestry

This land enters tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Vicious Rumors

Vicious Rumors deals 1 damage to each opponent. Each opponent discards a card, then mills a card. You gain 1 life.

Bojuka Bog

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

Azula, Cunning Usurper

Firebending 2 (Whenever this creature attacks, add {R}{R}. This mana lasts until end of combat.)
When Azula enters, target opponent exiles a nontoken creature they control, then they exile a nonland card from their graveyard.
During your turn, you may cast cards exiled with Azula and you may cast them as though they had flash. Mana of any type can be spent to cast those spells.

Geier Reach Sanitarium

{T}: Add {C}.
{2}, {T}: Each player draws a card, then discards a card.

Hama, the Bloodbender

When Hama enters, target opponent mills three cards. Exile up to one noncreature, nonland card from that player's graveyard. For as long as you control Hama, you may cast the exiled card during your turn by waterbending {X} rather than paying its mana cost, where X is its mana value. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)