Fathom Fleet Captain
Creature — Human Pirate
Menace
Whenever this creature attacks, if you control another nontoken Pirate, you may pay 
. If you do, create a 2/2 black Pirate creature token with menace.
"Join me, and take the world for yourself!"
Matt Stewart
Ixalan Promos (PXLN)
• #106sRulings
If you don't control another nontoken Pirate at the moment Fathom Fleet Captain attacks, its triggered ability won't trigger. If you don't control another nontoken Pirate as that ability resolves, you can't pay {2}.
(wotc • 2017-09-29)
While resolving Fathom Fleet Captain's triggered ability, you can't pay {2} multiple times to create more than one Pirate token.
(wotc • 2017-09-29)
Rulings
If you don't control another nontoken Pirate at the moment Fathom Fleet Captain attacks, its triggered ability won't trigger. If you don't control another nontoken Pirate as that ability resolves, you can't pay {2}.
(wotc • 2017-09-29)
While resolving Fathom Fleet Captain's triggered ability, you can't pay {2} multiple times to create more than one Pirate token.
(wotc • 2017-09-29)