Murmuring Mystic

Whenever you cast an instant or sorcery spell, create a 1/1 blue Bird Illusion creature token with flying.

Echo Mage

Level up {1}{U} ({1}{U}: Put a level counter on this. Level up only as a sorcery.)
LEVEL 2-3
2/4
{U}{U}, {T}: Copy target instant or sorcery spell. You may choose new targets for the copy.
LEVEL 4+
2/5
{U}{U}, {T}: Copy target instant or sorcery spell twice. You may choose new targets for the copies.

Zndrsplt, Eye of Wisdom

Partner with Okaun, Eye of Chaos (When this creature enters, target player may put Okaun into their hand from their library, then shuffle.)
At the beginning of combat on your turn, flip a coin until you lose a flip.
Whenever a player wins a coin flip, draw a card.

Voracious Reader

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Instant and sorcery spells you cast cost {1} less to cast.

Curious Homunculus

{T}: Add {C}. Spend this mana only to cast an instant or sorcery spell.
At the beginning of your upkeep, if there are three or more instant and/or sorcery cards in your graveyard, transform Curious Homunculus.

Curious Homunculus // Voracious Reader

Artful Dodge

Target creature can't be blocked this turn.
Flashback {U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Archmage Emeritus

Magecraft — Whenever you cast or copy an instant or sorcery spell, draw a card.

Plasma Elemental

Sun Quan, Lord of Wu

Creatures you control have horsemanship. (They can't be blocked except by creatures with horsemanship.)

Thunderclap Drake

Flying
Instant and sorcery spells you cast cost {1} less to cast.
{2}{U}, Sacrifice Thunderclap Drake: When you next cast an instant or sorcery spell this turn, copy it for each time you've cast your commander from the command zone this game. You may choose new targets for the copies.

Deekah, Fractal Theorist

Magecraft — Whenever you cast or copy an instant or sorcery spell, create a 0/0 green and blue Fractal creature token. Put X +1/+1 counters on it, where X is that spell's mana value.
{3}{U}: Target creature token can't be blocked this turn.

Plan the Heist

Surveil 3 if you have no cards in hand. Then draw three cards. (To surveil 3, look at the top three cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
Plot {3}{U} (You may pay {3}{U} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Candlestick

Equipped creature gets +1/+1 and has "Whenever this creature attacks, surveil 2." (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
{2}, Sacrifice Candlestick: Draw a card.
Equip {2}

Contingency Plan

Surveil 5. (Look at the top five cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Baral, Chief of Compliance

Instant and sorcery spells you cast cost {1} less to cast.
Whenever a spell or ability you control counters a spell, you may draw a card. If you do, discard a card.

Brain in a Jar

{1}, {T}: Put a charge counter on Brain in a Jar, then you may cast an instant or sorcery spell with mana value equal to the number of charge counters on Brain in a Jar from your hand without paying its mana cost.
{3}, {T}, Remove X charge counters from Brain in a Jar: Scry X.

Argivian Restoration

Return target artifact card from your graveyard to the battlefield.

Bubble Up

Put target instant or sorcery card from your graveyard on top of your library. (Then exile this card. You may cast the creature later from exile.)

Aquatic Alchemist

Whenever you cast your first instant or sorcery spell each turn, Aquatic Alchemist gets +2/+0 until end of turn.

Aquatic Alchemist // Bubble Up

Jace's Sanctum

Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast an instant or sorcery spell, scry 1.

God-Eternal Kefnet

Flying
You may reveal the first card you draw each turn as you draw it. Whenever you reveal an instant or sorcery card this way, copy that card and you may cast the copy. That copy costs {2} less to cast.
When God-Eternal Kefnet dies or is put into exile from the battlefield, you may put it into its owner's library third from the top.

Omnispell Adept

{2}{U}, {T}: You may cast an instant or sorcery spell from your hand without paying its mana cost.

Invocation of the Founders

Whenever you cast an instant or sorcery spell from your hand, you may copy that spell. You may choose new targets for the copy.

Invasion of Arcavios

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When Invasion of Arcavios enters, search your library, graveyard, and/or outside the game for an instant or sorcery card you own, reveal it, and put it into your hand. If you search your library this way, shuffle.

Invasion of Arcavios // Invocation of the Founders

Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Mirage Mirror

{2}: Mirage Mirror becomes a copy of target artifact, creature, enchantment, or land until end of turn.

Trail of Evidence

Whenever you cast an instant or sorcery spell, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Chakram Retriever

Partner with Chakram Slinger (When this creature enters, target player may put Chakram Slinger into their hand from their library, then shuffle.)
Whenever you cast a spell during your turn, untap target creature.

Thryx, the Sudden Storm

Flash (You may cast this spell any time you could cast an instant.)
Flying
Spells you cast with mana value 5 or greater cost {1} less to cast and can't be countered.

Talrand, Sky Summoner

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

Ghastly Discovery

Draw two cards, then discard a card.
Conspire (As you cast this spell, you may tap two untapped creatures you control that share a color with it. When you do, copy it.)

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.

Done

Tap up to two target creatures. Those creatures don't untap during their controller's next untap step.

Said

Return target instant or sorcery card from your graveyard to your hand.

Said // Done

Unblinking Observer

{T}: Add {U}. Spend this mana only to pay a disturb cost or cast an instant or sorcery spell.

Perfected Form

Aberrant Researcher

Flying
At the beginning of your upkeep, mill a card. If an instant or sorcery card was milled this way, transform Aberrant Researcher.

Aberrant Researcher // Perfected Form

Azcanta, the Sunken Ruin

(Transforms from Search for Azcanta.)
{T}: Add {U}.
{2}{U}, {T}: Look at the top four cards of your library. You may reveal a noncreature, nonland card from among them and put it into your hand. Put the rest on the bottom of your library in any order.

Search for Azcanta

At the beginning of your upkeep, surveil 1. Then if you have seven or more cards in your graveyard, you may transform Search for Azcanta. (Look at the top card of your library. You may put that card into your graveyard.)

Search for Azcanta // Azcanta, the Sunken Ruin

Lithoform Engine

{2}, {T}: Copy target activated or triggered ability you control. You may choose new targets for the copy.
{3}, {T}: Copy target instant or sorcery spell you control. You may choose new targets for the copy.
{4}, {T}: Copy target permanent spell you control. (The copy becomes a token.)

Abjure

As an additional cost to cast this spell, sacrifice a blue permanent.
Counter target spell.

Spell Satchel

Magecraft — Whenever you cast or copy an instant or sorcery spell, put a book counter on Spell Satchel.
{T}, Remove a book counter from Spell Satchel: Add {C}.
{3}, {T}, Remove three book counters from Spell Satchel: Draw a card.

Taigam's Scheming

River Song's Diary

Imprint — Whenever a player casts an instant or sorcery spell from their hand, exile it instead of putting it into a graveyard as it resolves.
At the beginning of your upkeep, if there are four or more cards exiled with River Song's Diary, choose one of them at random. You may cast it without paying its mana cost.

Sword of Once and Future

Equipped creature gets +2/+2 and has protection from blue and from black.
Whenever equipped creature deals combat damage to a player, surveil 2. Then you may cast an instant or sorcery spell with mana value 2 or less from your graveyard without paying its mana cost. If that spell would be put into your graveyard, exile it instead.
Equip {2}

Spellseeker

When Spellseeker enters, you may search your library for an instant or sorcery card with mana value 2 or less, reveal it, put it into your hand, then shuffle.

Aberrant Mind Sorcerer

Psionic Spells — When Aberrant Mind Sorcerer enters, choose target instant or sorcery card in your graveyard, then roll a d20.
1—9 | You may put that card on top of your library.
10—20 | Return that card to your hand.

Founding the Third Path

Read ahead (Choose a chapter and start with that many lore counters. Add one after your draw step. Skipped chapters don't trigger. Sacrifice after III.)
I — You may cast an instant or sorcery spell with mana value 1 or 2 from your hand without paying its mana cost.
II — Target player mills four cards.
III — Exile target instant or sorcery card from your graveyard. Copy it. You may cast the copy.

Pelargir Survivor

{T}: Add one mana of any color. Spend this mana only to cast an instant or sorcery spell.
{5}{U}, {T}: Target player mills three cards. (They put the top three cards of their library into their graveyard.)

Supreme Exemplar

Flying
Champion an Elemental (When this enters, sacrifice it unless you exile another Elemental you control. When this leaves the battlefield, that card returns to the battlefield.)

Insidious Will

Choose one —
• Counter target spell.
• You may choose new targets for target spell.
• Copy target instant or sorcery spell. You may choose new targets for the copy.

Treason of Isengard

Put up to one target instant or sorcery card from your graveyard on top of your library.
Amass Orcs 2. (To amass Orcs 2, put two +1/+1 counters on an Army you control. It's also an Orc. If you don't control an Army, create a 0/0 black Orc Army creature token first.)

Case of the Ransacked Lab

Instant and sorcery spells you cast cost {1} less to cast.
To solve — You've cast four or more instant and sorcery spells this turn. (If unsolved, solve at the beginning of your end step.)
Solved — Whenever you cast an instant or sorcery spell, draw a card.

Glamdring

Equipped creature has first strike and gets +1/+0 for each instant and sorcery card in your graveyard.
Whenever equipped creature deals combat damage to a player, you may cast an instant or sorcery spell from your hand with mana value less than or equal to that damage without paying its mana cost.
Equip {3}

Ancestral Reminiscence

Mulldrifter

Flying
When Mulldrifter enters, draw two cards.
Evoke {2}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)