Consider

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

Echoing Truth

Return target nonland permanent and all other permanents with the same name as that permanent to their owners' hands.

Cryptic Serpent

This spell costs {1} less to cast for each instant and sorcery card in your graveyard.

Murmuring Mystic

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

Insectile Aberration

Delver of Secrets

At the beginning of your upkeep, look at the top card of your library. You may reveal that card. If an instant or sorcery card is revealed this way, transform this creature.

Delver of Secrets // Insectile Aberration

Tolarian Terror

This spell costs {1} less to cast for each instant and sorcery card in your graveyard.
Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)

Thought Scour

Target player mills two cards.
Draw a card.

Counterspell

Hydroblast

Choose one —
• Counter target spell if it's red.
• Destroy target permanent if it's red.

Brainstorm

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

Ray of Erasure

Target player mills a card.
Draw a card at the beginning of the next turn's upkeep.

Blue Elemental Blast

Choose one —
• Counter target red spell.
• Destroy target red permanent.

Annul

Counter target artifact or enchantment spell.

Spell Pierce

Counter target noncreature spell unless its controller pays {2}.

Force Spike

Counter target spell unless its controller pays {1}.

Steel Sabotage

Choose one —
• Counter target artifact spell.
• Return target artifact to its owner's hand.

Lose Focus

Replicate {U} (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)
Counter target spell unless its controller pays {2}.

Boomerang

Return target permanent to its owner's hand.

Amass the Components

Draw three cards, then put a card from your hand on the bottom of your library.

Snow-Covered Island

Deep Analysis

Target player draws two cards.
Flashback—{1}{U}, Pay 3 life. (You may cast this card from your graveyard for its flashback cost. Then exile it.)