Charix, the Raging Isle

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

Mirrorshell Crab

Ward {3} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {3}.)
Channel — {2}{U}, Discard this card: Counter target spell or ability unless its controller pays {3}.

Dragon Turtle

Flash
Drag Below — When this creature enters, tap it and up to one target creature an opponent controls. They don't untap during their controllers' next untap steps.

Hermitic Nautilus

Vigilance
{1}{U}: This creature gets +3/-3 until end of turn.

Prismatic Lens

{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Fatestitcher

{T}: You may tap or untap another target permanent.
Unearth {U} ({U}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Spined Megalodon

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

Star Compass

This artifact enters tapped.
{T}: Add one mana of any color that a basic land you control could produce.

Thought Sponge

Flash
This creature enters with a number of +1/+1 counters on it equal to the greatest number of cards an opponent has drawn this turn.
When this creature dies, draw cards equal to its power.

Daggermaw Megalodon

Vigilance
Islandcycling {2} ({2}, Discard this card: Search your library for an Island card, reveal it, put it into your hand, then shuffle.)

Night Market

This land enters tapped. As it enters, choose a color.
{T}: Add one mana of the chosen color.
Cycling {3} ({3}, Discard this card: Draw a card.)

Fortress Crab

Planar Atlas

This artifact enters tapped.
When this artifact enters, you may look at the top four cards of your library. If you do, reveal up to one land card from among them, then put that card on top of your library and the rest on the bottom in a random order.
{T}: Add {C}.

Jokulmorder

Trample
This creature enters tapped.
When this creature enters, sacrifice it unless you sacrifice five lands.
This creature doesn't untap during your untap step.
Whenever you play an Island, you may untap this creature.

Corridor Monitor

When this creature enters, untap target artifact or creature you control.

Spellskite

{U/P}: Change a target of target spell or ability to this creature. ({U/P} can be paid with either {U} or 2 life.)

Memorial to Genius

This land enters tapped.
{T}: Add {U}.
{4}{U}, {T}, Sacrifice this land: Draw two cards.

Coldsteel Heart

This artifact enters tapped.
As this artifact enters, choose a color.
{T}: Add one mana of the chosen color.

Kraken Hatchling

Scuttling Doom Engine

This creature can't be blocked by creatures with power 2 or less.
When this creature dies, it deals 6 damage to target opponent or planeswalker.

The Surgical Bay

This land enters tapped.
{T}: Add {U}.
{1}{U}, {T}, Sacrifice this land: Draw a card.

Remote Isle

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

Coral Colony

Defender
{1}{U}, {T}: Target player mills X cards, where X is the number of creatures you control with defender. (To mill a card, a player puts the top card of their library into their graveyard.)

Mind Stone

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

Phyrexian Soulgorger

Cumulative upkeep—Sacrifice a creature. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)

Vizier of Tumbling Sands

{T}: Untap another target permanent.
Cycling {1}{U} ({1}{U}, Discard this card: Draw a card.)
When you cycle this card, untap target permanent.

Lonely Sandbar

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

The Reality Chip

You may look at the top card of your library any time.
As long as The Reality Chip is attached to a creature, you may play lands and cast spells from the top of your library.
Reconfigure {2}{U} ({2}{U}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Serpent of Yawning Depths

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

Wall of Deceit

Defender (This creature can't attack.)
{3}: Turn this creature face down.
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.)

Tablet of Compleation

{T}: Put an oil counter on this artifact.
{T}: Add {C}. Activate only if this artifact has two or more oil counters on it.
{1}, {T}: Draw a card. Activate only if this artifact has five or more oil counters on it.

Arcane Signet

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

Thought Vessel

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

Biolume Serpent

Sacrifice two Islands: This creature can't be blocked this turn.

Biolume Egg

Defender
When this creature enters, scry 2.
When you sacrifice this creature, return it to the battlefield transformed under its owner's control at the beginning of the next end step.

Biolume Egg // Biolume Serpent

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Cleaver Skaab

{3}, {T}, Sacrifice another Zombie: Create two tokens that are copies of the sacrificed creature.

Risen Riptide

Whenever you cast a kicked spell, this creature has base power and toughness 5/5 until end of turn.

Marjhan

This creature doesn't untap during your untap step.
{U}{U}, Sacrifice a creature: Untap this creature. Activate only during your upkeep.
This creature can't attack unless defending player controls an Island.
{U}{U}: This creature gets -1/-0 until end of turn and deals 1 damage to target attacking creature without flying.
When you control no Islands, sacrifice this creature.

Of One Mind

This spell costs {2} less to cast if you control a Human creature and a non-Human creature.
Draw two cards.

Taniwha

Trample
Phasing (This phases in or out before you untap during each of your untap steps. While it's phased out, it's treated as though it doesn't exist.)
At the beginning of your upkeep, all lands you control phase out. (They phase in before you untap during your next untap step.)

Aegis Turtle

Quantum Riddler

Flying
When this creature enters, draw a card.
As long as you have one or fewer cards in hand, if you would draw one or more cards, you draw that many cards plus one instead.
Warp {1}{U}

Thing from the Deep

Whenever this creature attacks, sacrifice it unless you sacrifice an Island.

Mechanozoa

When this creature enters, tap target artifact or creature an opponent controls and put a stun counter on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)
Warp {2}{U} (You may cast this card from your hand for its warp cost. Exile this creature at the beginning of the next end step, then you may cast it from exile on a later turn.)

Dormant Gomazoa

Flying
This creature enters tapped.
This creature doesn't untap during your untap step.
Whenever you become the target of a spell, you may untap this creature.

Tide Drifter

Devoid (This card has no color.)
Other colorless creatures you control get +0/+1.

Benthic Anomaly

Devoid (This card has no color.)
When you cast this spell, for each opponent, choose a creature that player controls. Create a token that's a copy of one of those creatures, except its power is equal to the total power of those creatures, its toughness is equal to the total toughness of those creatures, and it's a colorless Eldrazi creature.

Starbreach Whale

Flying
When this creature enters, surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
Warp {1}{U} (You may cast this card from your hand for its warp cost. Exile this creature at the beginning of the next end step, then you may cast it from exile on a later turn.)

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Armored Cancrix

Brackwater Elemental

When this creature attacks or blocks, sacrifice it at the beginning of the next end step.
Unearth {2}{U} ({2}{U}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Corrupted Shapeshifter

Devoid (This card has no color.)
As this creature enters, it becomes your choice of a 3/3 creature with flying, a 2/5 creature with vigilance, or a 0/12 creature with defender.

Angler Turtle

Hexproof
Creatures your opponents control attack each combat if able.

Canyon Crab

{1}{U}: This creature gets +2/-2 until end of turn.
At the beginning of your end step, if you haven't cast a spell from your hand this turn, draw a card, then discard a card.

Eluge, the Shoreless Sea

Eluge's power and toughness are each equal to the number of Islands you control.
Whenever Eluge enters or attacks, put a flood counter on target land. It's an Island in addition to its other types for as long as it has a flood counter on it.
The first instant or sorcery spell you cast each turn costs {U} (or {1}) less to cast for each land you control with a flood counter on it.

Eaten by Piranhas

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Enchanted creature loses all abilities and is a black Skeleton creature with base power and toughness 1/1. (It loses all other colors, card types, and creature types.)

Island

Crystacean

Flash (You may cast this spell any time you could cast an instant.)

Fractured Powerstone

{T}: Add {C}.
{T}: Roll the planar die. Activate only as a sorcery.

Slagwurm Armor

Equipped creature gets +0/+6.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery. This card enters unattached and stays on the battlefield if the creature leaves.)

Solemn Simulacrum

When this creature enters, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When this creature dies, you may draw a card.

Blighted Cataract

{T}: Add {C}.
{5}{U}, {T}, Sacrifice this land: Draw two cards.

Specimen Collector

When this creature enters, create a 1/1 green Squirrel creature token and a 0/3 blue Crab creature token.
When this creature dies, create a token that's a copy of target token you control.

Geralf, Visionary Stitcher

Zombies you control have flying.
{U}, {T}, Sacrifice another nontoken creature: Create an X/X blue Zombie creature token, where X is the sacrificed creature's toughness.

Ambling Stormshell

Ward {2}
Whenever this creature attacks, put three stun counters on it and draw three cards. (If a permanent with a stun counter would become untapped, remove one from it instead.)
Whenever you cast a Turtle spell, untap this creature.

Reservoir Kraken

Trample, ward {2}
At the beginning of each combat, if this creature is untapped, any opponent may tap an untapped creature they control. If they do, tap this creature and create a 1/1 blue Fish creature token with "This token can't be blocked."

Phyrexian Dreadnought

Trample
When this creature enters, sacrifice it unless you sacrifice any number of creatures with total power 12 or greater.

Riptide Turtle

Island Fish Jasconius

This creature doesn't untap during your untap step.
At the beginning of your upkeep, you may pay {U}{U}{U}. If you do, untap this creature.
This creature can't attack unless defending player controls an Island.
When you control no Islands, sacrifice this creature.

Sea Monster

This creature can't attack unless defending player controls an Island.

War Room

{T}: Add {C}.
{3}, {T}, Pay life equal to the number of colors in your commanders' color identity: Draw a card.

Crashing Drawbridge

Defender
{T}: Creatures you control gain haste until end of turn.

Caelorna, Coral Tyrant

Sapphire Medallion

Blue spells you cast cost {1} less to cast.

Surge Mare

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