Duke looked at the skull symbol and remembered that the Black Sail originated from pirates, so he could understand why the emblem was as it was.
This skull badge is also a demonized item and is exquisitely designed.
After learning how to use it, with a thought, the badge disappeared from the back of his hand, leaving a skull mark.
If he doesn't want this mark to appear, he can control it to hide.
This badge is a personal identity mark; only with it can one enter certain areas within the Black Sail.
For example, at the entrance's large whirlpool, only those with the badge can pass through; otherwise, they'd be crushed in the whirlpool.
If one does not have this badge, the guards outside will attack, making it impossible to reach the whirlpool.
Duke also learned the method to return to Black Sail; activate the Black Sail Badge with spiritual power and stand by the sea.
Soon after, a dark demon will come to guide him back onboard to Black Sail.
