Mental Note

Consider

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

Contaminated Aquifer

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

Rotten Reunion

Exile up to one target card from a graveyard. Create a 2/2 black Zombie creature token with decayed. (It can't block. When it attacks, sacrifice it at end of combat.)
Flashback {1}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Island

Steel Sabotage

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

Cast Down

Diabolic Edict

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}.)

Annul

Counter target artifact or enchantment spell.

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.

Counterspell

Suffocating Fumes

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

Spell Pierce

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

Fallaji Archaeologist

When Fallaji Archaeologist enters the battlefield, mill three cards. You may put a noncreature, nonland card from among the cards milled this way into your hand. If you don't, put a +1/+1 counter on Fallaji Archaeologist. (To mill a card, put the top card of your library into your graveyard.)

Blue Elemental Blast

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

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.)

Ice Tunnel

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

Unexpected Fangs

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

Brainstorm

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