Typedefense system

A ribcage is an open steel structure with two fighting decks with wooden or dacite paneled parapets. They are normally 24' high with fighting decks at 10' and 20'. Access to the two decks is by wooden ramps that can be pulled up to the deck above it. The bottom level, or the deck of the ship, is usually an open area so that crew can move about the area.

The Pillar of Horns has six ribcages, designated Ribcage Alpha to Alpha Foxtrot.

Each of these defensive towers, 30 feet square, 25 tall, six of them across the main deck, are a latticework of iron decks, catwalks, bridges, palisades, and fighting platforms. In times of battle, fifteen soldiers are stationed at each of these strong points. They include two mages, a healer, eight marines with crossbows, and five that help with reloading, hurling javelins, spears, or using pikes and halberds against any enemy that tries to get into the ribcage's two decks. The ribcages also include four ballistae, weapons too heavy and with too much recoil for even a giant to wield unmounted.

- from the Godspawn Saga