Consider

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

Serum Visions

Cephalid Coliseum

{T}: Add {U}. This land deals 1 damage to you.
Threshold — {U}, {T}, Sacrifice this land: Target player draws three cards, then discards three cards. Activate only if seven or more cards are in your graveyard.

Subtlety

Flash
Flying
When this creature enters, choose up to one target creature spell or planeswalker spell. Its owner puts it on their choice of the top or bottom of their library.
Evoke—Exile a blue card from your hand.

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

Spell Pierce

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

Suspend

Exile target creature and put two time counters on it. If it doesn't have suspend, it gains suspend. (At the beginning of its owner's upkeep, they remove a time counter. When the last is removed, they may play it without paying its mana cost. If it's a creature, it has haste.)

Faerie Conclave

This land enters tapped.
{T}: Add {U}.
{1}{U}: This land becomes a 2/1 blue Faerie creature with flying until end of turn. It's still a land.

Dress Down

Flash
When this enchantment enters, draw a card.
Creatures lose all abilities.
At the beginning of the end step, sacrifice this enchantment.

Chart a Course

Draw two cards. Then discard a card unless you attacked this turn.

Mystical Dispute

This spell costs {2} less to cast if it targets a blue spell.
Counter target spell unless its controller pays {3}.

Fading Hope

Return target creature to its owner's hand. If its mana value was 3 or less, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Counterspell

Cerulean Drake

Flying
Protection from red (This creature can't be blocked, targeted, dealt damage, enchanted, or equipped by anything red.)
Sacrifice this creature: Counter target spell that targets you.

Lonely Sandbar

This land enters tapped.
{T}: Add {U}.
Cycling {U} ({U}, Discard this card: Draw a card.)

Snapback

You may exile a blue card from your hand rather than pay this spell's mana cost.
Return target creature to its owner's hand.

Petty Theft

Return target nonland permanent an opponent controls to its owner's hand.

Brazen Borrower

Flash
Flying
This creature can block only creatures with flying.

Brazen Borrower // Petty Theft

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}.)

Unlicensed Hearse

{T}: Exile up to two target cards from a single graveyard.
Unlicensed Hearse's power and toughness are each equal to the number of cards exiled with it.
Crew 2

Echoing Truth

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

Glasspool Shore

Glasspool Mimic

You may have this creature enter as a copy of a creature you control, except it's a Shapeshifter Rogue in addition to its other types.

Glasspool Mimic // Glasspool Shore

Memory Lapse

Counter target spell. If that spell is countered this way, put it on top of its owner's library instead of into that player's graveyard.