Harbinger of the Seas

Arcane Denial

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep.
You draw a card at the beginning of the next turn's upkeep.

Spell Pierce

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

Scry 1. (Look at the top card of your library. You may put that card on the bottom.)
Draw a card.

Consider

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

Mana Leak

Counter target spell unless its controller pays {3}.

Spell Snare

Wavebreak Hippocamp

Whenever you cast your first spell during each opponent's turn, draw a card.

Standstill

When a player casts a spell, sacrifice this enchantment. If you do, each of that player's opponents draws three cards.

Snap

Return target creature to its owner's hand. Untap up to two lands.

Archmage's Charm

Choose one —
• Counter target spell.
• Target player draws two cards.
• Gain control of target nonland permanent with mana value 1 or less.

Brainstorm

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

Bident of Thassa

Whenever a creature you control deals combat damage to a player, you may draw a card.
{1}{U}, {T}: Creatures your opponents control attack this turn if able.

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

Talrand, Sky Summoner

Whenever you cast an instant or sorcery spell, create a 2/2 blue Drake creature token with flying.

Remand

Counter target spell. If that spell is countered this way, put it into its owner's hand instead of into that player's graveyard.
Draw a card.

Reality Shift

Exile target creature. Its controller manifests the top card of their library. (That player puts the top card of their library onto the battlefield face down as a 2/2 creature. If it's a creature card, it can be turned face up any time for its mana cost.)

Swan Song

Counter target enchantment, instant, or sorcery spell. Its controller creates a 2/2 blue Bird creature token with flying.

Mental Misstep

({U/P} can be paid with either {U} or 2 life.)
Counter target spell with mana value 1.

Peek

Look at target player's hand.
Draw a card.

Mystic Confluence

Choose three. You may choose the same mode more than once.
• Counter target spell unless its controller pays {3}.
• Return target creature to its owner's hand.
• Draw a card.

Abjure

As an additional cost to cast this spell, sacrifice a blue permanent.
Counter target spell.

Artistic Refusal

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Choose one or both —
• Counter target spell.
• Draw two cards, then discard a card.

Arcane Signet

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

Candlekeep Inspiration

Until end of turn, creatures you control have base power and toughness X/X, where X is the number of cards you own in exile and in your graveyard that are instant cards, are sorcery cards, and/or have an Adventure.

Annul

Counter target artifact or enchantment spell.

Baral, Chief of Compliance

Instant and sorcery spells you cast cost {1} less to cast.
Whenever a spell or ability you control counters a spell, you may draw a card. If you do, discard a card.

Eluge, the Shoreless Sea

Eluge's power and toughness are each equal to the number of Islands you control.
Whenever Eluge enters or attacks, put a flood counter on target land. It's an Island in addition to its other types for as long as it has a flood counter on it.
The first instant or sorcery spell you cast each turn costs {U} (or {1}) less to cast for each land you control with a flood counter on it.

Force Spike

Counter target spell unless its controller pays {1}.

Flow of Knowledge

Draw a card for each Island you control, then discard two cards.

Coastal Piracy

Whenever a creature you control deals combat damage to an opponent, you may draw a card.

Filter Out

Return all noncreature, nonland permanents to their owners' hands.

Deliberate

High Tide

Until end of turn, whenever a player taps an Island for mana, that player adds an additional {U}.

Sol Ring

Ponder

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

Wash Away

Cleave {1}{U}{U} (You may cast this spell for its cleave cost. If you do, remove the words in square brackets.)
Counter target spell [that wasn't cast from its owner's hand].

Daze

You may return an Island you control to its owner's hand rather than pay this spell's mana cost.
Counter target spell unless its controller pays {1}.

Voracious Reader

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Instant and sorcery spells you cast cost {1} less to cast.

Curious Homunculus

{T}: Add {C}. Spend this mana only to cast an instant or sorcery spell.
At the beginning of your upkeep, if there are three or more instant and/or sorcery cards in your graveyard, transform this creature.

Curious Homunculus // Voracious Reader

Counterspell

Lofty Denial

Counter target spell unless its controller pays {1}. If you control a creature with flying, counter that spell unless its controller pays {4} instead.

Flusterstorm

Counter target instant or sorcery spell unless its controller pays {1}.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

Dispel

Haughty Djinn

Flying
Haughty Djinn's power is equal to the number of instant and sorcery cards in your graveyard.
Instant and sorcery spells you cast cost {1} less to cast.

Quick Study

Foil

You may discard an Island card and another card rather than pay this spell's mana cost.
Counter target spell.

Negate

Miscast

Counter target instant or sorcery spell unless its controller pays {3}.

Murmuring Mystic

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

Strix Serenade

Counter target artifact, creature, or planeswalker spell. Its controller creates a 2/2 blue Bird creature token with flying.

Impulse

Look at the top four cards of your library. Put one of them into your hand and the rest on the bottom of your library in any order.

Envelop

Island

Pongify

Destroy target creature. It can't be regenerated. Its controller creates a 3/3 green Ape creature token.

Consign to Memory

Replicate {1} (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 triggered ability or colorless spell.

Hermes, Overseer of Elpis

Whenever you cast a noncreature spell, create a 1/1 blue Bird creature token with flying and vigilance.
Whenever you attack with one or more Birds, scry 2.

Cryptic Command

Choose two —
• Counter target spell.
• Return target permanent to its owner's hand.
• Tap all creatures your opponents control.
• Draw a card.