Jwari Scuttler

Purple-Crystal Crab

When Purple-Crystal Crab dies, draw a card.

King Crab

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

Horseshoe Crab

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.)

Riptide Crab

Vigilance
When Riptide Crab dies, draw a card.

Scuttletide

{1}, Discard a card: Create a 0/3 blue Crab creature token.
Delirium — Crabs you control get +1/+1 as long as there are four or more card types among cards in your graveyard.

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.

Derevi, Empyrial Tactician

Flying
When Derevi, Empyrial Tactician enters and whenever a creature you control deals combat damage to a player, you may tap or untap target permanent.
{1}{G}{W}{U}: Put Derevi onto the battlefield from the command zone.

Oraxid

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.)

Scuttling Sentinel

Flash
Vigilance
When Scuttling Sentinel enters, put a +1/+1 counter on another target creature you control. Until end of turn, that creature becomes a blue Crab in addition to its other types and gains hexproof. (It can't be the target of spells or abilities your opponents control.)

Fortress Crab

Iceberg Cancrix

Whenever another snow permanent you control enters, you may have target player mill two cards.

Hedron Crab

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

Salvage Scuttler

Whenever Salvage Scuttler attacks, return an artifact you control to its owner's hand.

Ancient Crab

Armored Cancrix

Simic Keyrune

{T}: Add {G} or {U}.
{G}{U}: Simic Keyrune becomes a 2/3 green and blue Crab artifact creature with hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Giant Crab

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