Stream of Thought

Target player mills four cards. You shuffle up to four cards from your graveyard into your library.
Replicate {2}{U}{U} (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)

Compelling Argument

Target player mills five cards.
Cycling {U} ({U}, Discard this card: Draw a card.)

Zada, Hedron Grinder

Whenever you cast an instant or sorcery spell that targets only Zada, Hedron Grinder, copy that spell for each other creature you control that the spell could target. Each copy targets a different one of those creatures.

Quintorius, Loremaster

Vigilance
At the beginning of your end step, exile target noncreature, nonland card from your graveyard. Create a 3/2 red and white Spirit creature token.
{1}{R}{W}, {T}, Sacrifice a Spirit: Choose target card exiled with Quintorius. You may cast that card this turn without paying its mana cost. If that spell would be put into a graveyard, put it on the bottom of its owner's library instead.

Baird, Argivian Recruiter

At the beginning of your end step, if you control a creature with power greater than its base power, create a 1/1 white Soldier creature token.

Jori En, Ruin Diver

Whenever you cast your second spell each turn, draw a card.

Taigam, Ojutai Master

Instant, sorcery, and Dragon spells you control can't be countered.
Whenever you cast an instant or sorcery spell from your hand, if Taigam, Ojutai Master attacked this turn, that spell gains rebound. (Exile the spell as it resolves. At the beginning of your next upkeep, you may cast that card from exile without paying its mana cost.)

Chill of Foreboding

Each player mills five cards.
Flashback {7}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Tower of Murmurs

{8}, {T}: Target player mills eight cards.

Teshar, Ancestor's Apostle

Flying
Whenever you cast a historic spell, return target creature card with mana value 3 or less from your graveyard to the battlefield. (Artifacts, legendaries, and Sagas are historic.)

Quintorius, Field Historian

Spirits you control get +1/+0.
Whenever one or more cards leave your graveyard, create a 3/2 red and white Spirit creature token.

Glacial Grasp

Tap target creature. Its controller mills two cards. That creature doesn't untap during its controller's next untap step. (They put the top two cards of their library into their graveyard.)
Draw a card.

Disturbing Conversion

Flash
Enchant creature
When Disturbing Conversion enters, each player mills two cards.
Enchanted creature gets -X/-0, where X is the number of cards in its controller's graveyard.

Fractured Sanity

Each opponent mills fourteen cards.
Cycling {1}{U} ({1}{U}, Discard this card: Draw a card.)
When you cycle Fractured Sanity, each opponent mills four cards.

Grindclock

{T}: Put a charge counter on Grindclock.
{T}: Target player mills X cards, where X is the number of charge counters on Grindclock.

Adriana, Captain of the Guard

Melee (Whenever this creature attacks, it gets +1/+1 until end of turn for each opponent you attacked this combat.)
Other creatures you control have melee. (If a creature has multiple instances of melee, each triggers separately.)

Ardenn, Intrepid Archaeologist

At the beginning of combat on your turn, you may attach any number of Auras and Equipment you control to target permanent or player.
Partner (You can have two commanders if both have partner.)

Bond of Insight

Each player mills four cards. Return up to two instant and/or sorcery cards from your graveyard to your hand. Exile Bond of Insight.

Psychic Spiral

Shuffle all cards from your graveyard into your library. Target player mills that many cards.

Weight of Memory

Draw three cards. Target player mills three cards.

Pia Nalaar, Consul of Revival

Thopters you control have haste.
Whenever you play a land from exile or cast a spell from exile, create a 1/1 colorless Thopter artifact creature token with flying.

Dream Twist

Target player mills three cards.
Flashback {1}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Winds of Rebuke

Return target nonland permanent to its owner's hand. Each player mills two cards.

Sevinne, the Chronoclasm

Prevent all damage that would be dealt to Sevinne, the Chronoclasm.
Whenever you cast your first instant or sorcery spell from your graveyard each turn, copy that spell. You may choose new targets for the copy.

Whetstone

Elsha of the Infinite

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
You may look at the top card of your library any time.
You may cast noncreature spells from the top of your library. If you cast a spell this way, you may cast it as though it had flash.

Fascination

Choose one —
• Each player draws X cards.
• Each player mills X cards.

Mind Sculpt

Jhoira, Ageless Innovator

{T}: Put two ingenuity counters on Jhoira, Ageless Innovator, then you may put an artifact card with mana value X or less from your hand onto the battlefield, where X is the number of ingenuity counters on Jhoira.

Baral and Kari Zev

First strike, menace
Whenever you cast your first instant or sorcery spell each turn, you may cast a spell with lesser mana value that shares a card type with it from your hand without paying its mana cost. If you don't, create First Mate Ragavan, a legendary 2/1 red Monkey Pirate creature token. It gains haste until end of turn.

Popular Entertainer

Commander creatures you own have "Whenever one or more creatures you control deal combat damage to a player, goad target creature that player controls." (Until your next turn, that creature attacks each combat if able and attacks a player other than you if able.)

Stitcher Geralf

{2}{U}, {T}: Each player mills three cards. Exile up to two creature cards put into graveyards this way. Create an X/X blue Zombie creature token, where X is the total power of the cards exiled this way.

Dreadwaters

Target player mills X cards, where X is the number of lands you control.

Worry Beads

At the beginning of each player's upkeep, that player mills a card.

Ghoulcaller's Bell

Gale, Waterdeep Prodigy

Whenever you cast an instant or sorcery spell from your hand, you may cast up to one target card of the other type from your graveyard. If a spell cast from your graveyard this way would be put into your graveyard, exile it instead.
Choose a Background (You can have a Background as a second commander.)

Cut Your Losses

Casualty 2 (As you cast this spell, you may sacrifice a creature with power 2 or greater. When you do, copy this spell and you may choose a new target for the copy.)
Target player mills half their library, rounded down.

Tome Scour

Livaan, Cultist of Tiamat

Whenever you cast a noncreature spell, target creature gets +X/+0 until end of turn, where X is that spell's mana value.
Choose a Background (You can have a Background as a second commander.)

Ayesha Tanaka, Armorer

Whenever Ayesha Tanaka, Armorer attacks, look at the top four cards of your library. You may put any number of artifact cards with mana value less than or equal to Ayesha's power from among them onto the battlefield tapped. Put the rest on the bottom of your library in a random order.
Ayesha can't be blocked as long as defending player controls three or more artifacts.

Drowned Secrets

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

General Ferrous Rokiric

Hexproof from monocolored
Whenever you cast a multicolored spell, create a 4/4 red and white Golem artifact creature token.

Talrand, Sky Summoner

Whenever you cast an instant or sorcery spell, create a 2/2 blue Drake creature token with flying.

Emry, Lurker of the Loch

This spell costs {1} less to cast for each artifact you control.
When Emry, Lurker of the Loch enters, mill four cards.
{T}: Choose target artifact card in your graveyard. You may cast that card this turn. (You still pay its costs. Timing rules still apply.)

Firkraag, Cunning Instigator

Flying, haste
Whenever one or more Dragons you control attack an opponent, goad target creature that player controls.
Whenever a creature deals combat damage to one of your opponents, if that creature had to attack this combat, you put a +1/+1 counter on Firkraag, Cunning Instigator and you draw a card.

Jace's Erasure

Whenever you draw a card, you may have target player mill a card.

Narset, Enlightened Exile

Creatures you control have prowess.
Whenever Narset, Enlightened Exile attacks, exile target noncreature, nonland card with mana value less than Narset's power from a graveyard and copy it. You may cast the copy without paying its mana cost.

Octavia, Living Thesis

This spell costs {8} less to cast if you have eight or more instant and/or sorcery cards in your graveyard.
Ward {8}
Magecraft — Whenever you cast or copy an instant or sorcery spell, target creature has base power and toughness 8/8 until end of turn.

Balmor, Battlemage Captain

Flying
Whenever you cast an instant or sorcery spell, creatures you control get +1/+0 and gain trample until end of turn.

Keening Stone

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

Curse of the Bloody Tome

Enchant player
At the beginning of enchanted player's upkeep, that player mills two cards.

Flaming Fist

Commander creatures you own have "Whenever this creature attacks, it gains double strike until end of turn."