Marinia: Mechanics

Crew of pirates: As this creature enters the battlefield, sacrifice it unless you have two or more pirates ride it. If this creature would die, sacrifice all creatures riding it. If there are no creatures riding it, sacrifice it. Used on 6 cards: Grand Warship, Broken-Down Ship, Haunted Ship, Ordinary Ship, The Bloody Pearl, Illusory Ship

This is a mechanic to represent pirates boarding a ship.

Boat: Whenever this creature attacks you may have another attacking creature become unblockable until end of turn. Used on 3 cards: Row Boat, Life Raft, Jungle River Boat

This is a mechanic used to represent pirates escaping in a smaller boat.

In card text or details pages, write the mechanic's code name (playtest name) between square brackets, like "[Crittercast]", "[Bushido 1]" or "[Delay 4 {2}{R}{R}]". It will be expanded to the mechanic's name plus reminder text, such as "Suspend 4 – {2} {r} {r} . (Rather than cast this spell from your hand,...)"
To expand a mechanic's name but not its reminder text, include parentheses at the end of the square brackets: "[Crittercast()]", "[Delay 9 {R}()]".