Equilibrium

Whenever you cast a creature spell, you may pay {1}. If you do, return target creature to its owner's hand.

Crystal Chimes

{3}, {T}, Sacrifice Crystal Chimes: Return all enchantment cards from your graveyard to your hand.

Whelming Wave

Return all creatures to their owners' hands except for Krakens, Leviathans, Octopuses, and Serpents.

Cunning Evasion

Whenever a creature you control becomes blocked, you may return it to its owner's hand.

Seal of Removal

Sacrifice Seal of Removal: Return target creature to its owner's hand.

Dire Fleet Daredevil

First strike
When Dire Fleet Daredevil enters, exile target instant or sorcery card from an opponent's graveyard. You may cast it this turn, and mana of any type can be spent to cast that spell. If that spell would be put into a graveyard, exile it instead.

Captain Vargus Wrath

Whenever Captain Vargus Wrath attacks, Pirates you control get +1/+1 until end of turn for each time you've cast a commander from the command zone this game.

Gemcutter Buccaneer

Whenever Gemcutter Buccaneer or another Pirate you control enters, create a tapped Treasure token.
Treasures you control are Equipment in addition to their other types and have "Equipped creature gets +2/+0," equip Pirate {1}, and equip {3}.

Cowardice

Whenever a creature becomes the target of a spell or ability, return that creature to its owner's hand. (It won't be affected by the spell or ability.)

Merchant Raiders

Whenever Merchant Raiders or another Pirate you control enters, tap up to one target creature. That creature doesn't untap during its controller's untap step for as long as you control Merchant Raiders.

Sigil of Sleep

Enchant creature
Whenever enchanted creature deals damage to a player, return target creature that player controls to its owner's hand.

Evacuation

Return all creatures to their owners' hands.

Expedite

Target creature gains haste until end of turn.
Draw a card.

Storm Fleet Sprinter

Haste
Storm Fleet Sprinter can't be blocked.

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Perplexing Test

Choose one —
• Return all creature tokens to their owners' hands.
• Return all nontoken creatures to their owners' hands.

Malcolm, Keen-Eyed Navigator

Flying
Whenever one or more Pirates you control deal damage to your opponents, you create a Treasure token for each opponent dealt damage. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Partner (You can have two commanders if both have partner.)

Siren Stormtamer

Flying
{U}, Sacrifice Siren Stormtamer: Counter target spell or ability that targets you or a creature you control.

Snap

Return target creature to its owner's hand. Untap up to two lands.

Aether Channeler

When Aether Channeler enters, choose one —
• Create a 1/1 white Bird creature token with flying.
• Return another target nonland permanent to its owner's hand.
• Draw a card.