Consider

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

Thousand-Year Storm

Whenever you cast an instant or sorcery spell, copy it for each other instant and sorcery spell you've cast before it this turn. You may choose new targets for the copies.

Ruby Medallion

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

Counterspell

Peek

Look at target player's hand.
Draw a card.

Archmage Emeritus

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

Storm-Kiln Artist

This creature gets +1/+0 for each artifact you control.
Magecraft — Whenever you cast or copy an instant or sorcery spell, create a Treasure token.

Coruscation Mage

Offspring {2} (You may pay an additional {2} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
Whenever you cast a noncreature spell, this creature deals 1 damage to each opponent.

Bident of Thassa

Whenever a creature you control deals combat damage to a player, you may draw a card.
{1}{U}, {T}: Creatures your opponents control attack this turn if able.

Whirlwind of Thought

Whenever you cast a noncreature spell, draw a card.

Past in Flames

Each instant and sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost.
Flashback {4}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Refocus

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

Sapphire Medallion

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

Stormcatch Mentor

Haste
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.

Mind's Desire

Shuffle your library. Then exile the top card of your library. Until end of turn, you may play that card without paying its mana cost.
Storm (When you cast this spell, copy it for each spell cast before it this turn.)

Cerulean Wisps

Target creature becomes blue until end of turn. Untap that creature.
Draw a card.

Archmage of Runes

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

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Hedron Archive

{T}: Add {C}{C}.
{2}, {T}, Sacrifice this artifact: Draw two cards.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice this artifact: Draw a card.

Bolt of Keranos

Bolt of Keranos deals 3 damage to any target. Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Repeated Reverberation

When you next cast an instant spell, cast a sorcery spell, or activate a loyalty ability this turn, copy that spell or ability twice. You may choose new targets for the copies.

Thought Vessel

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

Niv-Mizzet, Parun

This spell can't be countered.
Flying
Whenever you draw a card, Niv-Mizzet deals 1 damage to any target.
Whenever a player casts an instant or sorcery spell, you draw a card.

Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Dramatic Reversal

Untap all nonland permanents you control.

Boros Charm

Choose one —
• Boros Charm deals 4 damage to target player or planeswalker.
• Permanents you control gain indestructible until end of turn.
• Target creature gains double strike until end of turn.

Azorius Signet

Dovin's Veto

This spell can't be countered.
Counter target noncreature spell.

Arcane Denial

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep.
You draw a card at the beginning of the next turn's upkeep.

Izzet Signet

Windfall

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

Storm Skreelix

Flying
Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast an instant or sorcery spell, this creature gets +2/+0 until end of turn.

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Worn Powerstone

This artifact enters tapped.
{T}: Add {C}{C}.

Frantic Search

Draw two cards, then discard two cards. Untap up to three lands.

Arcane Signet

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

Freed from the Real

Enchant creature
{U}: Tap enchanted creature.
{U}: Untap enchanted creature.

Talisman of Creativity

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

Crackling Spellslinger

Flash
When this creature enters, if you cast it, the next instant or sorcery spell you cast this turn has storm. (When you cast that spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

Najal, the Storm Runner

You may cast sorcery spells as though they had flash.
Whenever Najal attacks, you may pay {2}. If you do, when you next cast an instant or sorcery spell this turn, copy it. You may choose new targets for the copy.

Ral, Storm Conduit

Whenever you cast or copy an instant or sorcery spell, Ral deals 1 damage to target opponent or planeswalker.
+2: Scry 1.
−2: When you next cast an instant or sorcery spell this turn, copy that spell. You may choose new targets for the copy.

Goblin Electromancer

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

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.

Izzet Charm

Choose one —
• Counter target noncreature spell unless its controller pays {2}.
• Izzet Charm deals 2 damage to target creature.
• Draw two cards, then discard two cards.

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Negate

Jeskai Ascendancy

Whenever you cast a noncreature spell, creatures you control get +1/+1 until end of turn. Untap those creatures.
Whenever you cast a noncreature spell, you may draw a card. If you do, discard a card.

Grapeshot

Grapeshot deals 1 damage to any target.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

Ponder

Look at the top three cards of your library, then put them back in any order. You may shuffle.
Draw a card.

Gitaxian Probe

({U/P} can be paid with either {U} or 2 life.)
Look at target player's hand.
Draw a card.

Tempest Technique

Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies. Copies become tokens.)
Enchant creature you control
Enchanted creature gets +1/+1 for each enchantment you control.

Snap

Return target creature to its owner's hand. Untap up to two lands.

Ignite Memories

Target player reveals a card at random from their hand. Ignite Memories deals damage to that player equal to that card's mana value.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

Elemental Eruption

Create a 4/4 red Dragon Elemental creature token with flying and prowess.
Storm (When you cast this spell, copy it for each spell cast before it this turn.)

Djeru's Resolve

Untap target creature. Prevent all damage that would be dealt to it this turn.
Cycling {2} ({2}, Discard this card: Draw a card.)

Guttersnipe

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

Boros Signet

Volcanic Awakening

Destroy target land.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

Gnostro, Voice of the Crags

{T}: Choose one. X is the number of spells you've cast this turn.
• Scry X.
• Gnostro deals X damage to target creature.
• You gain X life.

Deliberate

To Arms!

Untap all creatures you control.
Draw a card.

Thunderclap Drake

Flying
Instant and sorcery spells you cast cost {1} less to cast.
{2}{U}, Sacrifice this creature: 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.

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Aetherflux Reservoir

Whenever you cast a spell, you gain 1 life for each spell you've cast this turn.
Pay 50 life: This artifact deals 50 damage to any target.

Fiery Encore

Discard a card, then draw a card. When you discard a nonland card this way, Fiery Encore deals damage equal to that card's mana value to target creature or planeswalker.
Storm (When you cast this spell, copy it for each spell cast before it this turn.)

Kessig Flamebreather

Whenever you cast a noncreature spell, this creature deals 1 damage to each opponent.