Thassa's Intervention

Choose one —
• Look at the top X cards of your library. Put up to two of them into your hand and the rest on the bottom of your library in a random order.
• Counter target spell unless its controller pays twice {X}.

Tidal Force

At the beginning of each upkeep, you may tap or untap target permanent.

Drag Under

Return target creature to its owner's hand.
Draw a card.

Octoprophet

When Octoprophet enters, 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.)

Alluring Siren

{T}: Target creature an opponent controls attacks you this turn if able.

Lonely Sandbar

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

Colossal Whale

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Whenever Colossal Whale attacks, you may exile target creature defending player controls until Colossal Whale leaves the battlefield. (That creature returns under its owner's control.)

Capture Sphere

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
When Capture Sphere enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

Thassa's Emissary

Bestow {5}{U} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)
Whenever Thassa's Emissary or enchanted creature deals combat damage to a player, draw a card.
Enchanted creature gets +3/+3.

River's Rebuke

Return all nonland permanents target player controls to their owner's hand.

Scourge of Fleets

When Scourge of Fleets enters, return each creature your opponents control with toughness X or less to its owner's hand, where X is the number of Islands you control.

Thassa's Rebuff

Counter target spell unless its controller pays {X}, where X is your devotion to blue. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)

Nezahal, Primal Tide

This spell can't be countered.
You have no maximum hand size.
Whenever an opponent casts a noncreature spell, draw a card.
Discard three cards: Exile Nezahal, Primal Tide. Return it to the battlefield tapped under its owner's control at the beginning of the next end step.

Open into Wonder

X target creatures can't be blocked this turn. Until end of turn, those creatures gain "Whenever this creature deals combat damage to a player, draw a card."

Waker of Waves

Creatures your opponents control get -1/-0.
{1}{U}, Discard Waker of Waves: Look at the top two cards of your library. Put one of them into your hand and the other into your graveyard.

Archetype of Imagination

Creatures you control have flying.
Creatures your opponents control lose flying and can't have or gain flying.

Octopus Umbra

Enchant creature
Enchanted creature has base power and toughness 8/8 and has "Whenever this creature attacks, you may tap target creature with power 8 or less."
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Mesmerizing Benthid

When Mesmerizing Benthid enters, create two 0/2 blue Illusion creature tokens with "Whenever this creature blocks a creature, that creature doesn't untap during its controller's next untap step."
Mesmerizing Benthid has hexproof as long as you control an Illusion.

Kraken of the Straits

Creatures with power less than the number of Islands you control can't block Kraken of the Straits.

Wonder

Flying
As long as Wonder is in your graveyard and you control an Island, creatures you control have flying.

Fleet Swallower

Whenever Fleet Swallower attacks, target player mills half their library, rounded up.

Dreamstone Hedron

{T}: Add {C}{C}{C}.
{3}, {T}, Sacrifice Dreamstone Hedron: Draw three cards.

Cunning Evasion

Whenever a creature you control becomes blocked, you may return it to its owner's hand.

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.

Guard Gomazoa

Defender, flying
Prevent all combat damage that would be dealt to Guard Gomazoa.

Back from the Brink

Exile a creature card from your graveyard and pay its mana cost: Create a token that's a copy of that card. Activate only as a sorcery.

Heraldic Banner

As Heraldic Banner enters, choose a color.
Creatures you control of the chosen color get +1/+0.
{T}: Add one mana of the chosen color.

Keiga, the Tide Star

Flying
When Keiga, the Tide Star dies, gain control of target creature.

Counterspell

Drawn from Dreams

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 a random order.

Halimar Depths

Halimar Depths enters tapped.
When Halimar Depths enters, look at the top three cards of your library, then put them back in any order.
{T}: Add {U}.

Serpent of Yawning Depths

Krakens, Leviathans, Octopuses, and Serpents you control can't be blocked except by Krakens, Leviathans, Octopuses, and Serpents.

Mistford River Turtle

Whenever Mistford River Turtle attacks, another target attacking non-Human creature can't be blocked this turn.

Negate

Inkwell Leviathan

Trample
Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Shroud (This creature can't be the target of spells or abilities.)

Deep-Sea Kraken

Deep-Sea Kraken can't be blocked.
Suspend 9—{2}{U} (Rather than cast this card from your hand, you may pay {2}{U} and exile it with nine time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost. It has haste.)
Whenever an opponent casts a spell, if Deep-Sea Kraken is suspended, remove a time counter from it.

Deep Freeze

Enchant creature
Enchanted creature has base power and toughness 0/4, has defender, loses all other abilities, and is a blue Wall in addition to its other colors and types.

Coral Atoll

Coral Atoll enters tapped.
When Coral Atoll enters, sacrifice it unless you return an untapped Island you control to its owner's hand.
{T}: Add {C}{U}.

Reef Worm

When Reef Worm dies, create a 3/3 blue Fish creature token with "When this creature dies, create a 6/6 blue Whale creature token with 'When this creature dies, create a 9/9 blue Kraken creature token.'"

Frogify

Enchant creature
Enchanted creature loses all abilities and is a blue Frog creature with base power and toughness 1/1. (It loses all other card types and creature types.)

Whelming Wave

Return all creatures to their owners' hands except for Krakens, Leviathans, Octopuses, and Serpents.

Phase Dolphin

Whenever Phase Dolphin attacks, another target attacking creature can't be blocked this turn.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Paralyzing Grasp

Enchant creature
Enchanted creature doesn't untap during its controller's untap step.

Eon Frolicker

Flying
When Eon Frolicker enters, if you cast it, target opponent takes an extra turn after this one. Until your next turn, you and planeswalkers you control gain protection from that player. (You and planeswalkers you control can't be targeted, dealt damage, or enchanted by anything controlled by that player.)

Pursued Whale

When Pursued Whale enters, each opponent creates a 1/1 red Pirate creature token with "This creature can't block" and "Creatures you control attack each combat if able."
Spells your opponents cast that target Pursued Whale cost {3} more to cast.

Engulf the Shore

Return to their owners' hands all creatures with toughness less than or equal to the number of Islands you control.

Thassa's Ire

{3}{U}: You may tap or untap target creature.

Worn Powerstone

Worn Powerstone enters tapped.
{T}: Add {C}{C}.

Spined Megalodon

Hexproof (This creature can't be the target of spells or abilities your opponents control.)
Whenever Spined Megalodon attacks, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

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.

Kefnet's Monument

Blue creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, target creature an opponent controls doesn't untap during its controller's next untap step.

Kraken's Eye

Whenever a player casts a blue spell, you may gain 1 life.

Gaseous Form

Enchant creature
Prevent all combat damage that would be dealt to and dealt by enchanted creature.

Stern Dismissal

Return target creature or enchantment an opponent controls to its owner's hand.

Charix, the Raging Isle

Spells your opponents cast that target Charix, the Raging Isle cost {2} more to cast.
{3}: Charix gets +X/-X until end of turn, where X is the number of Islands you control.

Crush of Tentacles

Surge {3}{U}{U} (You may cast this spell for its surge cost if you or a teammate has cast another spell this turn.)
Return all nonland permanents to their owners' hands. If this spell's surge cost was paid, create an 8/8 blue Octopus creature token.

Ur-Golem's Eye

Retreat to Coralhelm

Landfall — Whenever a land you control enters, choose one —
• You may tap or untap target creature.
• Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Sigiled Starfish

{T}: Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Jace, Architect of Thought

+1: Until your next turn, whenever a creature an opponent controls attacks, it gets -1/-0 until end of turn.
−2: Reveal the top three cards of your library. An opponent separates those cards into two piles. Put one pile into your hand and the other on the bottom of your library in any order.
−8: For each player, search that player's library for a nonland card and exile it, then that player shuffles. You may cast those cards without paying their mana costs.

Corrupted Conscience

Enchant creature
You control enchanted creature.
Enchanted creature has infect. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Ugin's Insight

Scry X, where X is the highest mana value among permanents you control, then draw three cards.

Hedron Archive

{T}: Add {C}{C}.
{2}, {T}, Sacrifice Hedron Archive: Draw two cards.

Kiora Bests the Sea God

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Create an 8/8 blue Kraken creature token with hexproof.
II — Tap all nonland permanents target opponent controls. They don't untap during their controller's next untap step.
III — Gain control of target permanent an opponent controls. Untap it.

Spectral Shift

Choose one —
• Change the text of target spell or permanent by replacing all instances of one basic land type with another. (This effect lasts indefinitely.)
• Change the text of target spell or permanent by replacing all instances of one color word with another. (This effect lasts indefinitely.)
Entwine {2} (Choose both if you pay the entwine cost.)

Research the Deep

Draw a card. Clash with an opponent. If you win, return Research the Deep to its owner's hand. (Each clashing player reveals the top card of their library, then puts that card on the top or bottom. A player wins if their card had a higher mana value.)

Keep Safe

Counter target spell that targets a permanent you control.
Draw a card.

Quest for Ula's Temple

At the beginning of your upkeep, you may look at the top card of your library. If it's a creature card, you may reveal it and put a quest counter on Quest for Ula's Temple.
At the beginning of each end step, if there are three or more quest counters on Quest for Ula's Temple, you may put a Kraken, Leviathan, Octopus, or Serpent creature card from your hand onto the battlefield.

Callaphe, Beloved of the Sea

Callaphe's power is equal to your devotion to blue. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)
Creatures and enchantments you control have "Spells your opponents cast that target this permanent cost {1} more to cast."

Kasmina's Transmutation

Enchant creature
Enchanted creature loses all abilities and has base power and toughness 1/1.

Voracious Greatshark

Flash
When Voracious Greatshark enters, counter target artifact or creature spell.

Encrust

Enchant artifact or creature
Enchanted permanent doesn't untap during its controller's untap step and its activated abilities can't be activated.

Tolarian Kraken

Whenever you draw a card, you may pay {1}. When you do, you may tap or untap target creature.

Turn to Frog

Until end of turn, target creature loses all abilities and becomes a blue Frog with base power and toughness 1/1.

Whispersilk Cloak

Equipped creature can't be blocked and has shroud. (It can't be the target of spells or abilities.)
Equip {2}

Selective Snare

Return X target creatures of the creature type of your choice to their owner's hand.

Eel Umbra

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Enchanted creature gets +1/+1.
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Startling Development

Until end of turn, target creature becomes a blue Serpent with base power and toughness 4/4.
Cycling {1} ({1}, Discard this card: Draw a card.)

Lorthos, the Tidemaker

Whenever Lorthos, the Tidemaker attacks, you may pay {8}. If you do, tap up to eight target permanents. Those permanents don't untap during their controllers' next untap steps.

Tidebinder Mage

When Tidebinder Mage enters, tap target red or green creature an opponent controls. That creature doesn't untap during its controller's untap step for as long as you control Tidebinder Mage.

Thassa, God of the Sea

Indestructible
As long as your devotion to blue is less than five, Thassa isn't a creature. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)
At the beginning of your upkeep, scry 1.
{1}{U}: Target creature you control can't be blocked this turn.

Nyx Lotus

Nyx Lotus enters tapped.
{T}: Choose a color. Add an amount of mana of that color equal to your devotion to that color. (Your devotion to a color is the number of mana symbols of that color in the mana costs of permanents you control.)

Dismiss

Blessed Reincarnation

Exile target creature an opponent controls. That player reveals cards from the top of their library until a creature card is revealed. The player puts that card onto the battlefield, then shuffles the rest into their library.
Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)

Tromokratis

Tromokratis has hexproof unless it's attacking or blocking.
Tromokratis can't be blocked unless all creatures defending player controls block it. (If any creature that player controls doesn't block this creature, it can't be blocked.)

Realmwright

As Realmwright enters, choose a basic land type.
Lands you control are the chosen type in addition to their other types.

Hydroblast

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

Entrancing Melody

Gain control of target creature with mana value X.

Sol Ring

Dissolve

Counter target spell. Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Aqueous Form

Enchant creature
Enchanted creature can't be blocked.
Whenever enchanted creature attacks, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Thieving Otter

Whenever Thieving Otter deals damage to an opponent, draw a card.

Polymorph

Destroy target creature. It can't be regenerated. Its controller reveals cards from the top of their library until they reveal a creature card. The player puts that card onto the battlefield, then shuffles all other cards revealed this way into their library.

Void Stalker

{2}{U}, {T}: Put Void Stalker and target creature on top of their owners' libraries, then those players shuffle their libraries.

Crystacean

Omen of the Sea

Flash
When Omen of the Sea enters, scry 2, then draw a card.
{2}{U}, Sacrifice Omen of the Sea: Scry 2.

Read the Tides

Choose one —
• Draw three cards.
• Return up to two target creatures to their owners' hands.

Monastery Siege

As Monastery Siege enters, choose Khans or Dragons.
• Khans — At the beginning of your draw step, draw an additional card, then discard a card.
• Dragons — Spells your opponents cast that target you or a permanent you control cost {2} more to cast.

Traveler's Amulet

{1}, Sacrifice Traveler's Amulet: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.

Slinn Voda, the Rising Deep

Kicker {1}{U} (You may pay an additional {1}{U} as you cast this spell.)
When Slinn Voda, the Rising Deep enters, if it was kicked, return all creatures to their owners' hands except for Merfolk, Krakens, Leviathans, Octopuses, and Serpents.