The Phlogiston is a Tarkuusan prison barge. The metal-clad circular ship, over 500 meters in diameter, has an uncanny appearance, its featureless hull a jarring sight on the water as it moves without any visible means of propulsion. Though it is known to be a prison ship, the identities of those imprisoned within are unknown - even the number of guards and prisoners is a matter of conjecture. The Phlogiston always remains within the Bay of Tulzar, staying well within waters patrolled by Tarkuusan warships.