Arcane Signet

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

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.)

Gulf Squid

When Gulf Squid enters, tap all lands target player controls.

Sol Ring

Sand Squid

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
You may choose not to untap Sand Squid during your untap step.
{T}: Tap target creature. That creature doesn't untap during its controller's untap step for as long as Sand Squid remains tapped.

Ancient Crab

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.

Aethertide Whale

Flying
When Aethertide Whale enters, you get six {E} (energy counters).
Pay {E}{E}{E}{E}: Return Aethertide Whale to its owner's hand.

King Crab

{1}{U}, {T}: Put target green creature on top of its owner's library.

Great Whale

When Great Whale enters, untap up to seven lands.

Killer Whale

{U}: Killer Whale gains flying until end of turn.

Skyclave Squid

Defender
Landfall — Whenever a land you control enters, Skyclave Squid can attack this turn as though it didn't have defender.

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.

Ruin Crab

Landfall — Whenever a land you control enters, each opponent mills three cards. (To mill a card, a player puts the top card of their library into their graveyard.)

Mana Drain

Counter target spell. At the beginning of your next main phase, add an amount of {C} equal to that spell's mana value.

Wishcoin Crab

Wormfang Crab

Wormfang Crab can't be blocked.
When Wormfang Crab enters, an opponent chooses a permanent you control other than Wormfang Crab and exiles it.
When Wormfang Crab leaves the battlefield, return the exiled card to the battlefield under its owner's control.

Fortress Crab

Commander's Sphere

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

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.

Hedron Crab

Landfall — Whenever a land you control enters, target player mills three cards.

Purple-Crystal Crab

When Purple-Crystal Crab dies, draw a card.

Giant Crab

{U}: Giant Crab gains shroud until end of turn. (It can't be the target of spells or abilities.)

Long-Finned Skywhale

Flying
Long-Finned Skywhale can block only creatures with flying.

Crab Umbra

Enchant creature
{2}{U}: Untap enchanted creature.
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Horseshoe Crab

Chromeshell Crab

Morph {4}{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 Chromeshell Crab is turned face up, you may exchange control of target creature you control and target creature an opponent controls.