Spectral Sailor

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

Champion of Dusk

When Champion of Dusk enters, you draw X cards and you lose X life, where X is the number of Vampires you control.

Fathom Fleet Captain

Menace
Whenever Fathom Fleet Captain attacks, if you control another nontoken Pirate, you may pay {2}. If you do, create a 2/2 black Pirate creature token with menace.

Seafloor Oracle

Whenever a Merfolk you control deals combat damage to a player, draw a card.

Kinjalli's Caller

Dinosaur spells you cast cost {1} less to cast.

Earthshaker Dreadmaw

Trample
When Earthshaker Dreadmaw enters, draw a card for each other Dinosaur you control.

Corsair Captain

When this creature enters, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")
Other Pirates you control get +1/+1.

Dire Fleet Ravager

Menace, deathtouch
When Dire Fleet Ravager enters, each player loses a third of their life, rounded up.

Etchings of the Chosen

As Etchings of the Chosen enters, choose a creature type.
Creatures you control of the chosen type get +1/+1.
{1}, Sacrifice a creature of the chosen type: Target creature you control gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Drana's Emissary

Flying
At the beginning of your upkeep, each opponent loses 1 life and you gain 1 life.

Merrow Reejerey

Other Merfolk creatures you control get +1/+1.
Whenever you cast a Merfolk spell, you may tap or untap target permanent.

Palani's Hatcher

Other Dinosaurs you control have haste.
When Palani's Hatcher enters, create two 0/1 green Dinosaur Egg creature tokens.
At the beginning of combat on your turn, if you control one or more Eggs, sacrifice an Egg, then create a 3/3 green Dinosaur creature token.

Sanctum Seeker

Whenever a Vampire you control attacks, each opponent loses 1 life and you gain 1 life.

Legion Lieutenant

Thundering Spineback

Other Dinosaurs you control get +1/+1.
{5}{G}: Create a 3/3 green Dinosaur creature token with trample. (It can deal excess combat damage to the player or planeswalker it's attacking.)

Merfolk Sovereign

Other Merfolk creatures you control get +1/+1.
{T}: Target Merfolk creature can't be blocked this turn.

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.

Merfolk Mistbinder

Deeproot Waters

Whenever you cast a Merfolk spell, create a 1/1 blue Merfolk creature token with hexproof. (A creature with hexproof can't be the target of spells or abilities your opponents control.)