Ghost Pirate Rum Was First introduced in Build 123.4.1 and, it drops from Enemies in the dungeon Davy Jones's Locker and the Ghost Ship. It is very helpful for other classes as it allows the user to sneak undetected making the Demon Blade and the Staff of Extreme Prejudice more useful; it also promotes the Warrior class since, when using their ability, they can have the highest damage output of any sword class.
Example Screenshot (a paladin atacking an enraged Geb)