Consider

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

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.

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.

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.)

Surge of Brilliance

Paradox — Draw a card for each spell you've cast this turn from anywhere other than your hand.
Foretell {1}{U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Vega, the Watcher

Flying
Whenever you cast a spell from anywhere other than your hand, draw a card.

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

Swords to Plowshares

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

Sol Ring

Clockspinning

Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
Choose a counter on target permanent or suspended card. Remove that counter from that permanent or card or put another of those counters on it.

Command Tower

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

Third Path Iconoclast

Whenever you cast a noncreature spell, create a 1/1 colorless Soldier artifact creature token.

Jhoira's Timebug

{T}: Choose target permanent you control or suspended card you own. If that permanent or card has a time counter on it, you may remove a time counter from it or put another time counter on it.

Reverse the Polarity

Choose one —
• Counter all other spells.
• Switch each creature's power and toughness until end of turn.
• Creatures can't be blocked this turn.

Gandalf of the Secret Fire

Whenever you cast an instant or sorcery spell from your hand during an opponent's turn, exile that card with three time counters on it instead of putting it into your graveyard as it resolves. Then if the exiled card doesn't have suspend, it gains suspend. (At the beginning of your upkeep, remove a time counter from that card. When the last is removed, you may play it without paying its mana cost.)

Frantic Search

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

Archmage Emeritus

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

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Plains

Counterspell

Whirlwind of Thought

Whenever you cast a noncreature spell, draw a card.

Fact or Fiction

Reveal the top five cards of your library. An opponent separates those cards into two piles. Put one pile into your hand and the other into your graveyard.

Island

Brainstorm

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

Guttersnipe

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

Stroke of Midnight

Destroy target nonland permanent. Its controller creates a 1/1 white Human creature token.

Izzet Signet

Quick Study

Repulse

Return target creature to its owner's hand.
Draw a card.

Fiery Inscription

When Fiery Inscription enters the battlefield, the Ring tempts you.
Whenever you cast an instant or sorcery spell, Fiery Inscription deals 2 damage to each opponent.

Goblin Electromancer

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

Storm-Kiln Artist

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

Chaos Warp

The owner of target permanent shuffles it into their library, then reveals the top card of their library. If it's a permanent card, they put it onto the battlefield.

Mountain

Mystic Sanctuary

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

Ponder

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

Mystic Monastery

Mystic Monastery enters the battlefield tapped.
{T}: Add {U}, {R}, or {W}.

Reliquary Tower

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

Think Twice

Draw a card.
Flashback {2}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)