Capsize

Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
Return target permanent to its owner's hand.

Gray Harbor Merfolk

This creature can't be blocked.
This creature gets +2/+0 as long as you control a commander that's a creature or planeswalker.

Relic of Progenitus

{T}: Target player exiles a card from their graveyard.
{1}, Exile this artifact: Exile all graveyards. Draw a card.

Expedition Lookout

Defender
As long as an opponent has eight or more cards in their graveyard, this creature can attack as though it didn't have defender and it can't be blocked.

Skyline Cascade

This land enters tapped.
When this land enters, target creature an opponent controls doesn't untap during its controller's next untap step.
{T}: Add {U}.

Ghoulcaller's Bell

High Tide

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

Drowner of Secrets

Tap an untapped Merfolk you control: Target player mills a card.

Merfolk Looter

Ponder

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

Stonybrook Banneret

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Merfolk spells and Wizard spells you cast cost {1} less to cast.

Venture Deeper

Target player mills four cards. (Then exile this card. You may cast the creature later from exile.)

Merfolk Secretkeeper

Merfolk Secretkeeper // Venture Deeper

Merfolk Observer

When this creature enters, look at the top card of target player's library.

Serum Visions

Ink Dissolver

Kinship — At the beginning of your upkeep, you may look at the top card of your library. If it shares a creature type with this creature, you may reveal it. If you do, each opponent mills three cards.

Thought Scour

Target player mills two cards.
Draw a card.

Remote Isle

This land enters tapped.
{T}: Add {U}.
Cycling {2} ({2}, Discard this card: Draw a card.)

Coral Trickster

Morph {U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
When this creature is turned face up, you may tap or untap target permanent.

Merfolk Traders

When this creature enters, draw a card, then discard a card.

Mystic Sanctuary

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

Streambed Aquitects

{T}: Target Merfolk creature gets +1/+1 and gains islandwalk until end of turn. (It can't be blocked as long as defending player controls an Island.)
{T}: Target land becomes an Island until end of turn.

Halimar Depths

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

Merfolk Thaumaturgist

{T}: Switch target creature's power and toughness until end of turn.

Thought Vessel

You have no maximum hand size.
{T}: Add {C}.

Augur of Bolas

When this creature enters, look at the top three 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 any order.

Negate

Disrupt

Counter target instant or sorcery spell unless its controller pays {1}.
Draw a card.

Vodalian Arcanist

{T}: Add {C}. Spend this mana only to cast an instant or sorcery spell.

Tidal Visionary

{T}: Target creature becomes the color of your choice until end of turn.

Silvergill Douser

{T}: Target creature gets -X/-0 until end of turn, where X is the number of Merfolk and/or Faeries you control.

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.

Frantic Search

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

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.

Freed from the Real

Enchant creature
{U}: Tap enchanted creature.
{U}: Untap enchanted creature.

Stonybrook Angler

{1}{U}, {T}: You may tap or untap target creature.

Mind Sculpt

Curse of the Bloody Tome

Enchant player
At the beginning of enchanted player's upkeep, that player mills two cards.

Tidal Warrior

{T}: Target land becomes an Island until end of turn.

Portent

Look at the top three cards of target player's library, then put them back in any order. You may have that player shuffle.
Draw a card at the beginning of the next turn's upkeep.

Reef Shaman

{T}: Target land becomes the basic land type of your choice until end of turn.

Shore Up

Target creature you control gets +1/+1 and gains hexproof until end of turn. Untap it. (It can't be the target of spells or abilities your opponents control.)

Treasure Hunt

Reveal cards from the top of your library until you reveal a nonland card, then put all cards revealed this way into your hand.

Merrow Witsniper

When this creature enters, target player mills a card.

Jace's Erasure

Whenever you draw a card, you may have target player mill a card.

Drowner Initiate

Whenever a player casts a blue spell, you may pay {1}. If you do, target player mills two cards.

Whirlpool Rider

When this creature enters, shuffle the cards from your hand into your library, then draw that many cards.

Rootwater Mystic

{1}{U}: Look at the top card of target player's library.

Merrow Levitator

{T}: Target creature gains flying until end of turn.
Whenever you cast a blue spell, you may untap this creature.

Hidden Strings

You may tap or untap target permanent, then you may tap or untap another target permanent.
Cipher (Then you may exile this spell card encoded on a creature you control. Whenever that creature deals combat damage to a player, its controller may cast a copy of the encoded card without paying its mana cost.)

Merfolk Spy

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Whenever this creature deals combat damage to a player, that player reveals a card at random from their hand.

Tome Scour

Didn't Say Please

Counter target spell. Its controller mills three cards.

Dispel

Merfolk Mesmerist

Lonely Sandbar

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

Thought Collapse

Sage's Row Denizen

Whenever another blue creature you control enters, target player mills two cards.

Voda Sea Scavenger

Domain — When this creature enters, look at the top X cards of your library, where X is the number of basic land types among lands you control. You may put one of those cards on top of your library. Put the rest on the bottom of your library in a random order.

Chronic Flooding

Enchant land
Whenever enchanted land becomes tapped, its controller mills three cards.

Inkfathom Divers

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
When this creature enters, look at the top four cards of your library, then put them back in any order.

Grasp of Phantoms

Put target creature on top of its owner's library.
Flashback {7}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Volshe Tideturner

{T}: Add {U}. Spend this mana only to cast an instant or sorcery spell or a kicked spell.

Dramatic Reversal

Untap all nonland permanents you control.

Island

Vodalian Mage

{U}, {T}: Counter target spell unless its controller pays {1}.

Dreadwaters

Target player mills X cards, where X is the number of lands you control.

Decanter of Endless Water

You have no maximum hand size.
{T}: Add one mana of any color.

Dive Down

Target creature you control gets +0/+3 and gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Salvager of Secrets

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

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.)

Mind Stone

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

Sea Scryer

Muddle the Mixture

Counter target instant or sorcery spell.
Transmute {1}{U}{U} ({1}{U}{U}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)