Ixalan

Dreamcaller Siren | Creature | Siren Pirate | Flash Flying Dreamcaller Siren can block only creatures with flying. When Dreamcaller Siren enters the battlefield, if you control another Pirate, tap up to two target nonland permanents. | Eric Deschamps

Herald of Secret Streams | Creature | Merfolk Warrior | Creatures you control with +1/+1 counters on them can't be blocked. | Sara Winters

Hostage Taker | Creature | Human Pirate | When Hostage Taker enters the battlefield, exile another target creature or artifact until Hostage Taker leaves the battlefield. You may cast that card for as long as it remains exiled, and you may spend mana as though it were mana of any type to cast that spell. | Wayne Reynolds