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.

Declaration of Naught

As Declaration of Naught enters, choose a card name.
{U}: Counter target spell with the chosen name.

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.)

Nadir Kraken

Whenever you draw a card, you may pay {1}. If you do, put a +1/+1 counter on Nadir Kraken and create a 1/1 blue Tentacle creature token.

Curator's Ward

Enchant permanent
Enchanted permanent has hexproof.
When enchanted permanent leaves the battlefield, if it was historic, draw two cards. (Artifacts, legendaries, and Sagas are historic.)

Castle Vantress

Castle Vantress enters tapped unless you control an Island.
{T}: Add {U}.
{2}{U}{U}, {T}: Scry 2.

Artful Dodge

Target creature can't be blocked this turn.
Flashback {U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Lilting Refrain

At the beginning of your upkeep, you may put a verse counter on Lilting Refrain.
Sacrifice Lilting Refrain: Counter target spell unless its controller pays {X}, where X is the number of verse counters on Lilting Refrain.

Gadwick, the Wizened

When Gadwick, the Wizened enters, draw X cards.
Whenever you cast a blue spell, tap target nonland permanent an opponent controls.

Aetherize

Return all attacking creatures to their owner's hand.

Sphinx of Magosi

Flying
{2}{U}: Draw a card, then put a +1/+1 counter on Sphinx of Magosi.

Witching Well

When Witching Well 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.)
{3}{U}, Sacrifice Witching Well: Draw two cards.

Dissipate

Counter target spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

Mystic Sanctuary

({T}: Add {U}.)
Mystic Sanctuary enters tapped unless you control three or more other Islands.
When Mystic Sanctuary enters untapped, you may put target instant or sorcery card from your graveyard on top of your library.

Ominous Seas

Whenever you draw a card, put a foreshadow counter on Ominous Seas.
Remove eight foreshadow counters from Ominous Seas: Create an 8/8 blue Kraken creature token.
Cycling {2} ({2}, Discard this card: Draw a card.)

Arcanis the Omnipotent

{T}: Draw three cards.
{2}{U}{U}: Return Arcanis the Omnipotent to its owner's hand.

Seal of Removal

Sacrifice Seal of Removal: Return target creature to its owner's hand.

Hesitation

When a player casts a spell, sacrifice Hesitation and counter that spell.

Quickling

Flash (You may cast this spell any time you could cast an instant.)
Flying
When Quickling enters, sacrifice it unless you return another creature you control to its owner's hand.

Burnished Hart

{3}, Sacrifice Burnished Hart: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Ichthyomorphosis

Enchant creature
Enchanted creature loses all abilities and is a blue Fish with base power and toughness 0/1.

Imprisoned in the Moon

Enchant creature, land, or planeswalker
Enchanted permanent is a colorless land with "{T}: Add {C}" and loses all other card types and abilities.

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.

Faerie Seer

War Tax

{X}{U}: This turn, creatures can't attack unless their controller pays {X} for each attacking creature they control.

Kasmina's Transmutation

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

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."

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

Reconnaissance Mission

Whenever a creature you control deals combat damage to a player, you may draw a card.
Cycling {2} ({2}, Discard this card: Draw a card.)

Archetype of Imagination

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

Atemsis, All-Seeing

Flying
{2}{U}, {T}: Draw two cards, then discard a card.
Whenever Atemsis, All-Seeing deals damage to an opponent, you may reveal your hand. If cards with at least six different mana values are revealed this way, that player loses the game.

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.)

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.)

Tempest Djinn

Flying
Tempest Djinn gets +1/+0 for each basic Island you control.

Draining Whelk

Flash
Flying
When Draining Whelk enters, counter target spell. Put X +1/+1 counters on Draining Whelk, where X is that spell's mana value.

Mystic Veil

You may cast Mystic Veil as though it had flash. If you cast it any time a sorcery couldn't have been cast, the controller of the permanent it becomes sacrifices it at the beginning of the next cleanup step.
Enchant creature
Enchanted creature has shroud. (It can't be the target of spells or abilities.)

Mirrormade

You may have Mirrormade enter as a copy of any artifact or enchantment on the battlefield.

Lonely Sandbar

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

Emergence Zone

{T}: Add {C}.
{1}, {T}, Sacrifice Emergence Zone: You may cast spells this turn as though they had flash.

Fireshrieker

Equipped creature has double strike. (It deals both first-strike and regular combat damage.)
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Protective Bubble

Enchant creature
Enchanted creature can't be blocked and has shroud. (It can't be the target of spells or abilities.)

Myriad Landscape

Myriad Landscape enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice Myriad Landscape: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Buoyancy

Flash
Enchant creature
Enchanted creature has flying.

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.)

Future Sight

Play with the top card of your library revealed.
You may play lands and cast spells from the top of your library.

Island

Rootwater Shaman

You may cast Aura spells with enchant creature as though they had flash.

Thought Reflection

If you would draw a card, draw two cards instead.

Rewind

Counter target spell. Untap up to four lands.

Unwind

Counter target noncreature spell. Untap up to three lands.

Protean Thaumaturge

Constellation — Whenever an enchantment you control enters, you may have Protean Thaumaturge become a copy of another target creature, except it has this ability.

Wash Out

Return all permanents of the color of your choice to their owners' hands.

Kasmina, Enigmatic Mentor

Spells your opponents cast that target a creature or planeswalker you control cost {2} more to cast.
−2: Create a 2/2 blue Wizard creature token. Draw a card, then discard a card.

Narset, Parter of Veils

Each opponent can't draw more than one card each turn.
−2: Look at the top four cards of your library. You may reveal a noncreature, nonland card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Phantom Wings

Enchant creature
Enchanted creature has flying.
Sacrifice Phantom Wings: Return enchanted creature to its owner's hand.

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Aether Tunnel

Enchant creature
Enchanted creature gets +1/+0 and can't be blocked.

Counterspell

Curse of the Swine

Exile X target creatures. For each creature exiled this way, its controller creates a 2/2 green Boar creature token.

Altar of the Pantheon

Your devotion to each color and each combination of colors is increased by one.
{T}: Add one mana of any color. If you control a God, a Demigod, or a legendary enchantment, you gain 1 life.

Invisibility

Enchant creature
Enchanted creature can't be blocked except by Walls.

Moonring Island

({T}: Add {U}.)
Moonring Island enters tapped.
{U}, {T}: Look at the top card of target player's library. Activate only if you control two or more blue permanents.

Naiad of Hidden Coves

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

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: 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.)

Sea Gate Oracle

When Sea Gate Oracle enters, 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.

Soaring Seacliff

Soaring Seacliff enters tapped.
When Soaring Seacliff enters, target creature gains flying until end of turn.
{T}: Add {U}.

Flood of Tears

Return all nonland permanents to their owners' hands. If you return four or more nontoken permanents you control this way, you may put a permanent card from your hand onto the battlefield.

Siren Stormtamer

Flying
{U}, Sacrifice Siren Stormtamer: Counter target spell or ability that targets you or a creature you control.