Young Pyromancer

Whenever you cast an instant or sorcery spell, create a 1/1 red Elemental creature token.

Thrill of Possibility

As an additional cost to cast this spell, discard a card.
Draw two cards.

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.)

Teach by Example

({U/R} can be paid with either {U} or {R}.)
When you next cast an instant or sorcery spell this turn, copy that spell. You may choose new targets for the copy.

Maestros Theater

When Maestros Theater enters, sacrifice it. When you do, search your library for a basic Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle and you gain 1 life.

Shivan Reef

{T}: Add {C}.
{T}: Add {U} or {R}. Shivan Reef deals 1 damage to you.

Mountain

Izzet Signet

Narset's Reversal

Copy target instant or sorcery spell, then return it to its owner's hand. You may choose new targets for the copy.

Psychic Corrosion

Whenever you draw a card, each opponent mills two cards.

Prismari Campus

Prismari Campus enters tapped.
{T}: Add {U} or {R}.
{4}, {T}: Scry 1.

Maddening Cacophony

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

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.

Increasing Confusion

Target player mills X cards. If this spell was cast from a graveyard, that player mills twice that many cards instead.
Flashback {X}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Errant, Street Artist

Flash
Defender, haste
{1}{U}, {T}: Copy target spell you control that wasn't cast. You may choose new targets for the copy.

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.

Scry 1. (Look at the top card of your library. You may put that card on the bottom.)
Draw a card.

Drowned Secrets

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

Hedron Crab

Landfall — Whenever a land you control enters, target player mills three cards.

Island

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 more.

Mystic Sanctuary

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

Drown in Dreams

Choose one. If you control a commander as you cast this spell, you may choose both instead.
• Target player draws X cards.
• Target player mills twice X cards.

Bonus Round

Until end of turn, whenever a player casts an instant or sorcery spell, that player copies it and may choose new targets for the copy.

Goblin Electromancer

Instant and sorcery spells you cast cost {1} less to cast.

Solve the Equation

Search your library for an instant or sorcery card, reveal it, put it into your hand, then shuffle.

Guttersnipe

Whenever you cast an instant or sorcery spell, this creature deals 2 damage to each opponent.

Thriving Bluff

Thriving Bluff enters tapped. As it enters, choose a color other than red.
{T}: Add {R} or one mana of the chosen color.

Consider

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

Memory Erosion

Whenever an opponent casts a spell, that player mills two cards.

Counterspell

Mind Sculpt

Rootha, Mercurial Artist

{2}, Return Rootha, Mercurial Artist to its owner's hand: Copy target instant or sorcery spell you control. You may choose new targets for the copy.

Thriving Isle

Thriving Isle enters tapped. As it enters, choose a color other than blue.
{T}: Add {U} or one mana of the chosen color.

Sulfur Falls

Sulfur Falls enters tapped unless you control an Island or a Mountain.
{T}: Add {U} or {R}.

Fraying Sanity

Enchant player
At the beginning of each end step, enchanted player mills X cards, where X is the number of cards put into their graveyard from anywhere this turn.

Command Tower

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

Frostboil Snarl

As Frostboil Snarl enters, you may reveal an Island or Mountain card from your hand. If you don't, Frostboil Snarl enters tapped.
{T}: Add {U} or {R}.

Reverberate

Copy target instant or sorcery spell. You may choose new targets for the copy.

Prismari Command

Choose two —
• Prismari Command deals 2 damage to any target.
• Target player draws two cards, then discards two cards.
• Target player creates a Treasure token.
• Destroy target artifact.

Twinning Staff

If you would copy a spell one or more times, instead copy it that many times plus an additional time. You may choose new targets for the additional copy.
{7}, {T}: Copy target instant or sorcery spell you control. You may choose new targets for the copy.

Sweet Oblivion

Target player mills four cards.
Escape—{3}{U}, Exile four other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)

Galvanic Iteration

When you next cast an instant or sorcery spell this turn, copy that spell. You may choose new targets for the copy.
Flashback {1}{U}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Increasing Vengeance

Copy target instant or sorcery spell you control. If this spell was cast from a graveyard, copy that spell twice instead. You may choose new targets for the copies.
Flashback {3}{R}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Dualcaster Mage

Flash
When Dualcaster Mage enters, copy target instant or sorcery spell. You may choose new targets for the copy.

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.)