The successor of the Katoballistae, the Onager was yet another important invention to the Atlanteans. Compared to the Arcuballista, and Cheiroballista, Mangonels did not utilize a bow-system, but instead a sling-system, which would be passed down and eventually used by the Ancient Indians, and Romans.

Due to the lack of advanced enemies which were mostly primitive tribals, or cannibal giants, Mangonels fell out of fashion for being impractical, they would however find new life during the Atlantean Civil and Rebirth Wars under King Kastor.