Eel Umbra

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Enchanted creature gets +1/+1.
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Riddlekeeper

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

Minamo, School at Water's Edge

{T}: Add {U}.
{U}, {T}: Untap target legendary permanent.

Slip Out the Back

Put a +1/+1 counter on target creature. It phases out. (Treat it and anything attached to it as though they don't exist until its controller's next turn.)

Jace's Phantasm

Flying
This creature gets +4/+4 as long as an opponent has ten or more cards in their graveyard.

Thought Scour

Target player mills two cards.
Draw a card.

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.)

Trinket Mage

When this creature enters, you may search your library for an artifact card with mana value 1 or less, reveal that card, put it into your hand, then shuffle.

Maddening Cacophony

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

Blade of Selves

Equipped creature has myriad. (Whenever it attacks, for each opponent other than defending player, you may create a token copy that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)
Equip {4}

Genji Glove

Equipped creature has double strike.
Whenever equipped creature attacks, if it's the first combat phase of the turn, untap it. After this phase, there is an additional combat phase.
Equip {3}

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.

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}

Trophy Mage

When this creature enters, you may search your library for an artifact card with mana value 3, reveal it, put it into your hand, then shuffle.

Fog Bank

Defender (This creature can't attack.)
Flying
Prevent all combat damage that would be dealt to and dealt by this creature.

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.)

Assault Suit

Equipped creature gets +2/+2, has haste, can't attack you or planeswalkers you control, and can't be sacrificed.
At the beginning of each opponent's upkeep, you may have that player gain control of equipped creature until end of turn. If you do, untap it.
Equip {3}

Sands of Delirium

Relic Golem

This creature can't attack or block unless an opponent has eight or more cards in their graveyard.
{2}, {T}: Target player mills two cards. (They put the top two cards of their library into their graveyard.)

Transit Mage

When this creature enters, you may search your library for an artifact card with mana value 4 or 5, reveal it, put it into your hand, then shuffle.

Archway of Innovation

This land enters tapped unless you control an Island.
{T}: Add {U}.
{U}, {T}: The next spell you cast this turn has improvise. (Your artifacts can help cast that spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)

Mindcrank

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

Fireshrieker

Equipped creature has double strike. (It deals both first-strike and regular combat damage.)
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Maze of Ith

{T}: Untap target attacking creature. Prevent all combat damage that would be dealt to and dealt by that creature this turn.

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.

Whispersilk Cloak

Equipped creature can't be blocked and has shroud. (It can't be the target of spells or abilities.)
Equip {2}

Helm of the Host

At the beginning of combat on your turn, create a token that's a copy of equipped creature, except the token isn't legendary. That token gains haste.
Equip {5}

Commander's Plate

Equipped creature gets +3/+3 and has protection from each color that's not in your commander's color identity.
Equip commander {3}
Equip {5}

Sapphire Medallion

Blue spells you cast cost {1} less to cast.

Altar of the Brood

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

Spark Double

You may have this creature enter as a copy of a creature or planeswalker you control, except it enters with an additional +1/+1 counter on it if it's a creature, it enters with an additional loyalty counter on it if it's a planeswalker, and it isn't legendary.

Treasure Mage

When this creature enters, you may search your library for an artifact card with mana value 6 or greater, reveal it, put it into your hand, then shuffle.

Auton Soldier

You may have this creature enter as a copy of any creature on the battlefield, except it isn't legendary, is an artifact in addition to its other types, and has myriad. (Whenever it attacks, for each opponent other than defending player, you may create a token copy that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)

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.

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.

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.)

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.)

Fleet Swallower

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

Soulless Jailer

Permanent cards in graveyards can't enter the battlefield.
Players can't cast noncreature spells from graveyards or exile.

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.)

Excalibur, Sword of Eden

This spell costs {X} less to cast, where X is the total mana value of historic permanents you control. (Artifacts, legendaries, and Sagas are historic.)
Equipped creature gets +10/+0 and has vigilance.
Equip legendary creature {2}

Tribute Mage

When this creature enters, you may search your library for an artifact card with mana value 2, reveal that card, put it into your hand, then shuffle.

Witness Protection

Enchant creature
Enchanted creature loses all abilities and is a green and white Citizen creature with base power and toughness 1/1 named Legitimate Businessperson. (It loses all other colors, card types, creature types, and names.)

Keening Stone

{5}, {T}: Target player mills X cards, where X is the number of cards in that player's graveyard.

Propaganda

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

Sea Gate, Reborn

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

Sea Gate Restoration

Draw cards equal to the number of cards in your hand plus one. You have no maximum hand size for the rest of the game.

Sea Gate Restoration // Sea Gate, Reborn

Didn't Say Please

Counter target spell. Its controller mills three cards.

Crawlspace

No more than two creatures can attack you each combat.

Manic Scribe

When this creature enters, each opponent mills three cards.
Delirium — At the beginning of each opponent's upkeep, if there are four or more card types among cards in your graveyard, that player mills three cards.

Silver Myr

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.)

Cyclonic Rift

Return target nonland permanent you don't control to its owner's hand.
Overload {6}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Rhystic Study

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

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.

Imprisoned in the Moon

Enchant creature, land, or planeswalker
Enchanted permanent is a colorless land with "{T}: Add {C}" and loses all other card types and abilities.

Visions of Beyond

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

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.

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.

Sceptre of Eternal Glory

{T}: Add one mana of any color.
{T}: Add three mana of any one color. Activate only if you control three or more lands with the same name.

Brass Knuckles

When you cast this spell, copy it. (The copy becomes a token.)
Equipped creature has double strike as long as two or more Equipment are attached to it.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Back to Basics

Nonbasic lands don't untap during their controllers' untap steps.

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.)

Winged Boots

Equipped creature has flying and ward {4}. (Whenever equipped creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {4}.)
Equip {1}

Etherium Sculptor

Artifact spells you cast cost {1} less to cast.

Island

Thought Collapse

Scourge of Fleets

When this creature enters, return each creature your opponents control with toughness X or less to its owner's hand, where X is the number of Islands you control.

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.)