The Fort Oink consists of three castle towers, one of which is controlled by a large pig demon at the center, while the two side towers are occupied by Skuttlers. All three towers have propellers to keep the entire building in the air, as well as blue crystalline structures beneath them. The pig monster's big tower in the middle is also decorated with metallic ears, a large closed door, and its curly tail can be seen poking out behind the tower's base. They're similar to the Belunka in which they're airborne transports, but can only be damaged by hitting the pig face or tail.
Fort Oinks first appear during both the aerial and ground missions of Chapter 19, The Lightning Chariot. And made there final appearence in the land battle of Chapter 24: The Three Trials. Like Belunkas, they are not very common enemies, but will spawn other monsters until they are defeated. Despite their high defenses, light arrows from the Three Sacred Treasures can penetrate the armored bodies of Fort Oinks with relative ease. Fort Oinks are much like Belunkas in many respects apart from their physical appearance. What they lack in size though, they make up in strength and durability.
Fort Oink was originally designed to transport Underworld troops to the battlefield. However, mistakes were made and it now fires its passengers as ammunition. At least the Underworld now knows to measure twice and cut once.