Entrancing Melody

Gain control of target creature with mana value X.

Favorable Winds

Creatures you control with flying get +1/+1.

Fleet Swallower

Whenever this creature attacks, target player mills half their library, rounded up.

Headwater Sentries

Herald of Secret Streams

Creatures you control with +1/+1 counters on them can't be blocked.

Bishop's Soldier

Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Illusion

Jace, Cunning Castaway

+1: Whenever one or more creatures you control deal combat damage to a player this turn, draw a card, then discard a card.
−2: Create a 2/2 blue Illusion creature token with "When this token becomes the target of a spell, sacrifice it."
−5: Create two tokens that are copies of Jace, except they're not legendary.

Kopala, Warden of Waves

Spells your opponents cast that target a Merfolk you control cost {2} more to cast.
Abilities your opponents activate that target a Merfolk you control cost {2} more to activate.

Lookout's Dispersal

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

Navigator's Ruin

Raid — At the beginning of your end step, if you attacked this turn, target opponent mills four cards.

One With the Wind

Enchant creature
Enchanted creature gets +2/+2 and has flying.

Scry 1. (Look at the top card of your library. You may put that card on the bottom.)
Draw a card.

Overflowing Insight

Perilous Voyage

Return target nonland permanent you don't control to its owner's hand. If its mana value was 2 or less, scry 2.

Treasure

Pirate's Prize

Draw two cards. Create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Prosperous Pirates

When this creature enters, create two Treasure tokens. (They're artifacts with "{T}, Sacrifice this token: Add one mana of any color.")

Ixalan