Kitesail Freebooter

Flying
When Kitesail Freebooter enters, target opponent reveals their hand. You choose a noncreature, nonland card from it. Exile that card until Kitesail Freebooter leaves the battlefield.

City of Brass

Whenever City of Brass becomes tapped, it deals 1 damage to you.
{T}: Add one mana of any color.

Changeling Outcast

Changeling (This card is every creature type.)
Changeling Outcast can't block and can't be blocked.

Lookout's Dispersal

This spell costs {1} less to cast if you control a Pirate.
Counter target spell unless its controller pays {4}.

Spectral Sailor

Flash (You may cast this spell any time you could cast an instant.)
Flying
{3}{U}: Draw a card.

Ruin Raider

Raid — At the beginning of your end step, if you attacked this turn, reveal the top card of your library and put that card into your hand. You lose life equal to the card's mana value.

Admiral Beckett Brass

Other Pirates you control get +1/+1.
At the beginning of your end step, gain control of target nonland permanent controlled by a player who was dealt combat damage by three or more Pirates this turn.

Mountain

Tetsuko Umezawa, Fugitive

Creatures you control with power or toughness 1 or less can't be blocked.

Ragavan, Nimble Pilferer

Whenever Ragavan, Nimble Pilferer deals combat damage to a player, create a Treasure token and exile the top card of that player's library. Until end of turn, you may cast that card.
Dash {1}{R} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)

Swamp

Forerunner of the Coalition

When Forerunner of the Coalition enters, you may search your library for a Pirate card, reveal it, then shuffle and put that card on top.
Whenever another Pirate you control enters, each opponent loses 1 life.

Fiery Cannonade

Fiery Cannonade deals 2 damage to each non-Pirate creature.

Dire Fleet Poisoner

Flash
Deathtouch
When Dire Fleet Poisoner enters, target attacking Pirate you control gets +1/+1 and gains deathtouch until end of turn.

Siren Stormtamer

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

Dire Fleet Captain

Whenever Dire Fleet Captain attacks, it gets +1/+1 until end of turn for each other attacking Pirate.