The Skewer Cannon is a giant turret installed atop a pillar at the end of Fortress Wahnen's exterior outline. The weapon is a regular metallic cannon with red and gold linings, plus four long spikes coming from one of its side. Hiryu first observes it from atop a rooftop before descending and destroying it.
The Skewer Cannon can move its turret up and down to aim directly at Hiryu, shooting a fireball at him. Outside of being supported by small flying enemies constantly dropping bombs on Hiryu, it has no other means of attack. It is also harmless to direct contact in spite of its spikes and name, so Hiryu can actually stand next to it and damage it unopposed.