Consider

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

Brainstorm

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

Gurmag Angler

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)

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 Delver of Secrets.

Delver of Secrets // Insectile Aberration

Deem Inferior

This spell costs {1} less to cast for each card you've drawn this turn.
The owner of target nonland permanent puts it into their library second from the top or on the bottom.

Ice Tunnel

({T}: Add {U} or {B}.)
Ice Tunnel enters tapped.

Snooping Newsie

When Snooping Newsie enters, mill two cards. (Put the top two cards of your library into your graveyard.)
As long as there are five or more mana values among cards in your graveyard, Snooping Newsie gets +1/+1 and has lifelink.

Steel Sabotage

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

Careful Study

Unexpected Fangs

Put a +1/+1 counter and a lifelink counter on target creature.

Counterspell

Crawl from the Cellar

Return target creature card from your graveyard to your hand. Put a +1/+1 counter on up to one target Zombie you control.
Flashback {3}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Sneaky Snacker

Flying
When you draw your third card in a turn, return Sneaky Snacker from your graveyard to the battlefield tapped.

Nihil Spellbomb

{T}, Sacrifice Nihil Spellbomb: Exile target player's graveyard.
When Nihil Spellbomb is put into a graveyard from the battlefield, you may pay {B}. If you do, draw a card.

Contaminated Aquifer

({T}: Add {U} or {B}.)
Contaminated Aquifer enters tapped.

Hydroblast

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

Cast Down

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.)

Spell Pierce

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

Thought Scour

Target player mills two cards.
Draw a card.

Suffocating Fumes

Creatures your opponents control get -1/-1 until end of turn.
Cycling {2} ({2}, Discard this card: Draw a card.)

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}.)

Agony Warp

Target creature gets -3/-0 until end of turn.
Target creature gets -0/-3 until end of turn.