Stormtide Leviathan

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
All lands are Islands in addition to their other types.
Creatures without flying or islandwalk can't attack.

Brainstorm

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

Rimefire Torque

As this artifact enters, choose a creature type.
Whenever a permanent you control of the chosen type enters, put a charge counter on this artifact.
{T}, Remove three charge counters from this artifact: When you next cast an instant or sorcery spell this turn, copy it. You may choose new targets for the copy.

Frantic Search

Draw two cards, then discard two cards. Untap up to three lands.

Favorable Winds

Creatures you control with flying get +1/+1.

Ponder

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

Midnight Clock

{T}: Add {U}.
{2}{U}: Put an hour counter on this artifact.
At the beginning of each upkeep, put an hour counter on this artifact.
When the twelfth hour counter is put on this artifact, shuffle your hand and graveyard into your library, then draw seven cards. Exile this artifact.

Shark Typhoon

Whenever you cast a noncreature spell, create an X/X blue Shark creature token with flying, where X is that spell's mana value.
Cycling {X}{1}{U} ({X}{1}{U}, Discard this card: Draw a card.)
When you cycle this card, create an X/X blue Shark creature token with flying.

Talrand, Sky Summoner

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

Runechanter's Pike

Equipped creature has first strike and gets +X/+0, where X is the number of instant and sorcery cards in your graveyard.
Equip {2}

Island

Sky Diamond

This artifact enters tapped.
{T}: Add {U}.

Wavebreak Hippocamp

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

Arcane Signet

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

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.

Flow of Knowledge

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

Gale, Waterdeep Prodigy

Whenever you cast an instant or sorcery spell from your hand, you may cast up to one target card of the other type from your graveyard. If a spell cast from your graveyard this way would be put into your graveyard, exile it instead.
Choose a Background (You can have a Background as a second commander.)

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.

Silundi Isle

Silundi Vision

Look at the top six cards of your library. You may reveal an instant or sorcery card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Silundi Vision // Silundi Isle

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.)

High Tide

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

Think Twice

Draw a card.
Flashback {2}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Curiosity Crafter

Flying
You have no maximum hand size.
Whenever a creature token you control deals combat damage to a player, draw a card.

Wayfarer's Bauble

{2}, {T}, Sacrifice this artifact: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Geyser Drake

Flying
During turns other than yours, spells you cast cost {1} less to cast.

Fact or Fiction

Reveal the top five cards of your library. An opponent separates those cards into two piles. Put one pile into your hand and the other into your graveyard.

Archaeomancer

When this creature enters, return target instant or sorcery card from your graveyard to your hand.

Winged Words

This spell costs {1} less to cast if you control a creature with flying.
Draw two cards.

Serum Visions

Consider

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

Silver Myr

Niblis of Frost

Flying
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever you cast an instant or sorcery spell, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.

Call to Mind

Return target instant or sorcery card from your graveyard to your hand.

Chart a Course

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

Bender's Waterskin

Untap this artifact during each other player's untap step.
{T}: Add one mana of any color.

Murmuring Mystic

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

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.

Octavia, Living Thesis

This spell costs {8} less to cast if you have eight or more instant and/or sorcery cards in your graveyard.
Ward {8}
Magecraft — Whenever you cast or copy an instant or sorcery spell, target creature has base power and toughness 8/8 until end of turn.

Alandra, Sky Dreamer

Whenever you draw your second card each turn, create a 2/2 blue Drake creature token with flying.
Whenever you draw your fifth card each turn, Alandra and Drakes you control each get +X/+X until end of turn, where X is the number of cards in your hand.

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.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice this artifact: Draw a card.

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.

Distant Melody

Choose a creature type. Draw a card for each permanent you control of that type.

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

Rise from the Tides

Create a tapped 2/2 black Zombie creature token for each instant and sorcery card in your graveyard.

Archmage Emeritus

Magecraft — Whenever you cast or copy an instant or sorcery spell, draw a card.

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.

Wizard's Retort

This spell costs {1} less to cast if you control a Wizard.
Counter target spell.

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.

Anticipate

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

Thought Scour

Target player mills two cards.
Draw a card.

Gravitational Shift

Creatures with flying get +2/+0.
Creatures without flying get -2/-0.

Windreader Sphinx

Flying
Whenever a creature with flying attacks, you may draw a card.

Trawler Drake

Flying
This creature enters with an oil counter on it.
This creature gets +1/+1 for each oil counter on it.
Whenever you cast a noncreature spell, put an oil counter on this creature.

Mocking Sprite

Flying
Instant and sorcery spells you cast cost {1} less to cast.

Archmage of Runes

Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast an instant or sorcery spell, draw a card.

Treasure Cruise

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

Disdainful Stroke

Counter target spell with mana value 4 or greater.

Dig Through Time

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Look at the top seven cards of your library. Put two of them into your hand and the rest on the bottom of your library in any order.

Snap

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

Peregrine Drake

Flying
When this creature enters, untap up to five lands.

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

Sleight of Hand

Look at the top two cards of your library. Put one of them into your hand and the other on the bottom of your library.

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)