Prairie Stream

({T}: Add {W} or {U}.)
Prairie Stream enters tapped unless you control two or more basic lands.

Murkfiend Liege

Other green creatures you control get +1/+1.
Other blue creatures you control get +1/+1.
Untap all green and/or blue creatures you control during each other player's untap step.

Deepglow Skate

When Deepglow Skate enters, double the number of each kind of counter on any number of target permanents.

Unblinking Observer

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

Talisman of Curiosity

{T}: Add {C}.
{T}: Add {G} or {U}. Talisman of Curiosity deals 1 damage to you.

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.)

Revenge of the Drowned

Target creature's owner puts it on their choice of the top or bottom of their library. You create a 2/2 black Zombie creature token with decayed. (It can't block. When it attacks, sacrifice it at end of combat.)

Bounding Krasis

Flash (You may cast this spell any time you could cast an instant.)
When Bounding Krasis enters, you may tap or untap target creature.

Talisman of Unity

{T}: Add {C}.
{T}: Add {G} or {W}. Talisman of Unity deals 1 damage to you.

Bant Charm

Choose one —
• Destroy target artifact.
• Put target creature on the bottom of its owner's library.
• Counter target instant spell.

Clue

{2}, Sacrifice this artifact: Draw a card.

Spring Splasher

Whenever Spring Splasher attacks, target creature defending player controls gets -3/-0 until end of turn.

Tanglepool Bridge

Tanglepool Bridge enters tapped.
Indestructible
{T}: Add {G} or {U}.

Forest

Sungrass Prairie

Expendable Lackey

{1}{U}, Exile Expendable Lackey from your graveyard: Create a 1/1 blue Fish creature token with "This creature can't be blocked." Activate only as a sorcery.

Sol Ring

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.)

Stream of Thought

Target player mills four cards. You shuffle up to four cards from your graveyard into your library.
Replicate {2}{U}{U} (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)

Simic Signet

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Skybridge Towers

Skybridge Towers enters tapped.
{T}: Add {W} or {U}.
{2}{W}{U}, {T}, Sacrifice Skybridge Towers: Draw a card.

Harmonize

Talisman of Progress

{T}: Add {C}.
{T}: Add {W} or {U}. Talisman of Progress deals 1 damage to you.

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.

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.'"

Tribute to the Wild

Each opponent sacrifices an artifact or enchantment of their choice.

Floodhound

{3}, {T}: Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Skitter Eel

{2}{U}: Adapt 2. (If this creature has no +1/+1 counters on it, put two +1/+1 counters on it.)

Fumigate

Destroy all creatures. You gain 1 life for each creature destroyed this way.

Morska, Undersea Sleuth

You have no maximum hand size.
At the beginning of your upkeep, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Whenever you draw your second card each turn, put two +1/+1 counters on Morska, Undersea Sleuth.

Loan Shark

When Loan Shark enters, if you've cast two or more spells this turn, draw a card.
Plot {3}{U} (You may pay {3}{U} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Hook-Haunt Drifter

Flying
If Hook-Haunt Drifter would be put into a graveyard from anywhere, exile it instead.

Baithook Angler

Disturb {1}{U} (You may cast this card from your graveyard transformed for its disturb cost.)

Baithook Angler // Hook-Haunt Drifter

Render Silent

Counter target spell. Its controller can't cast spells this turn.

Exotic Pets

Create two 1/1 blue Fish creature tokens with "This creature can't be blocked." Then for each kind of counter among creatures you control, put a counter of that kind on either of those tokens.

Fish

Whale

When this creature dies, create a 9/9 blue Kraken creature token.

Lumbering Falls

Lumbering Falls enters tapped.
{T}: Add {G} or {U}.
{2}{G}{U}: Lumbering Falls becomes a 3/3 green and blue Elemental creature with hexproof until end of turn. It's still a land.

Prophetic Prism

When Prophetic Prism enters, draw a card.
{1}, {T}: Add one mana of any color.

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Unwind

Counter target noncreature spell. Untap up to three lands.

Mulldrifter

Flying
When Mulldrifter enters, draw two cards.
Evoke {2}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

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."

Breaching Hippocamp

Flash (You may cast this spell any time you could cast an instant.)
When Breaching Hippocamp enters, untap another target creature you control.

Human Soldier

Shambleshark

Flash (You may cast this spell any time you could cast an instant.)
Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)

Zombie

Ichthyomorphosis

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

Have

Plains

Wilt

Destroy target artifact or enchantment.
Cycling {2} ({2}, Discard this card: Draw a card.)

Vivid Flying Fish

Vivid Flying Fish has flying as long as it's attacking. (It can't be blocked except by creatures with flying or reach.)

Gone Missing

Put target permanent on top of its owner's library.
Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Tidal Barracuda

Any player may cast spells as though they had flash.
Your opponents can't cast spells during your turn.

Kraken of the Straits

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

Aetherize

Return all attacking creatures to their owner's hand.

Final-Word Phantom

Flash
Flying
During each opponent's end step, you may cast spells as though they had flash.

Mystic Skyfish

Whenever you draw your second card each turn, Mystic Skyfish gains flying until end of turn.

Castle Vantress

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

Out of the Way

This spell costs {2} less to cast if it targets a green permanent.
Return target nonland permanent an opponent controls to its owner's hand.
Draw a card.

Bubble Smuggler

Disguise {5}{U} (You may cast this card face down for {3} as a 2/2 creature with ward {2}. Turn it face up any time for its disguise cost.)
As Bubble Smuggler is turned face up, put four +1/+1 counters on it.

Faerie Conclave

Faerie Conclave enters tapped.
{T}: Add {U}.
{1}{U}: Faerie Conclave becomes a 2/1 blue Faerie creature with flying until end of turn. It's still a land.

Sleep with the Fishes

Enchant creature
When Sleep with the Fishes enters, tap enchanted creature and you create a 1/1 blue Fish creature token with "This creature can't be blocked."
Enchanted creature doesn't untap during its controller's untap step.

Surge Mare

Surge Mare can't be blocked by green creatures.
Whenever Surge Mare deals damage to an opponent, you may draw a card. If you do, discard a card.
{1}{U}: Surge Mare gets +2/-2 until end of turn.

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}.

Sharktocrab

{2}{G}{U}: Adapt 1. (If this creature has no +1/+1 counters on it, put a +1/+1 counter on it.)
Whenever one or more +1/+1 counters are put on Sharktocrab, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.

Undersea Invader

Flash (You may cast this spell any time you could cast an instant.)
Undersea Invader enters tapped.

Armed with Proof

When Armed with Proof enters, investigate twice. (To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Clues you control are Equipment in addition to their other types and have "Equipped creature gets +2/+0" and equip {2}.

Simic Growth Chamber

Simic Growth Chamber enters tapped.
When Simic Growth Chamber enters, return a land you control to its owner's hand.
{T}: Add {G}{U}.

Island

Battering Krasis

Trample
Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)

Desert of the Mindful

Desert of the Mindful enters tapped.
{T}: Add {U}.
Cycling {1}{U} ({1}{U}, Discard this card: Draw a card.)

Sea-Dasher Octopus

Mutate {1}{U} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Flash
Whenever this creature deals combat damage to a player, draw a card.

Yavimaya Coast

{T}: Add {C}.
{T}: Add {G} or {U}. Yavimaya Coast deals 1 damage to you.

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.

Tatyova, Benthic Druid

Landfall — Whenever a land you control enters, you gain 1 life and draw a card.

Blufferfish

{3}{U}: An opponent tells you a statement about themselves and secretly notes whether it's true or false. You guess which it is. If you guessed correctly, Blufferfish gets +2/+0 and can't be blocked this turn.

Seaside Citadel

Seaside Citadel enters tapped.
{T}: Add {G}, {W}, or {U}.

Growth Spiral

Draw a card. You may put a land card from your hand onto the battlefield.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Aboleth Spawn

Flash
Ward {2}
Probing Telepathy — Whenever a creature entering under an opponent's control causes a triggered ability of that creature to trigger, you may copy that ability. You may choose new targets for the copy.

Ulvenwald Mysteries

Whenever a nontoken creature you control dies, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Whenever you sacrifice a Clue, create a 1/1 white Human Soldier creature token.

Lonely Sandbar

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

Plasm Capture

Counter target spell. At the beginning of your next first main phase, add X mana in any combination of colors, where X is that spell's mana value.

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.)

Acquisition Octopus

Whenever Acquisition Octopus or equipped creature deals combat damage to a player, draw a card.
Reconfigure {2} ({2}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Arcane Signet

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

Grisly Anglerfish

{6}: Creatures your opponents control attack this turn if able.

Grizzled Angler

{T}: Mill two cards. Then if there is a colorless creature card in your graveyard, transform Grizzled Angler.

Grizzled Angler // Grisly Anglerfish

Hinterland Harbor

Hinterland Harbor enters tapped unless you control a Forest or an Island.
{T}: Add {G} or {U}.

Elder Deep-Fiend

Flash
Emerge {5}{U}{U} (You may cast this spell by sacrificing a creature and paying the emerge cost reduced by that creature's mana value.)
When you cast this spell, tap up to four target permanents.

Vitalize

Search the Premises

Whenever a creature attacks you or a planeswalker you control, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")