Ballista (Earth-2213)

The ballista (plural ballistae) is a large crossbow-type weapon that employs torsional force to propel projectiles, which vary from arrows, darts, and harpoon, at a much faster velocity and rate than a normal catapult.

Overview
Many of these weapons are mounted in rotating platforms onboard Land of Fire Navy warships, used to fire a metal projectile into the hull of enemy ships below the water life. After the hull has been breached, the projectile will open up in order to prevent it from pulling free.

Ballistae could also be found at the maximum security facility Boiling Rock to stop Chit Sang, Mae and Nozio from escaping.