Every Roman Centuria within a Legion was equipped with a Light Bolt shooter (either Scorpion or Manuballista). These were manned by regular Legionaries and used in the field or defensively from forts or during sieges. They were capable of hurling a large dart or bolt at much longer ranges than the typical bow and added some devastating long range, heavy hitting firepower to any Roman Legion. There is a useful image on Trajan’s column depicting this Bolt-shooter with cylindrical drums laying siege to a Dacian hillfort. You get a lot of bits to really customise each figure and make your bolt-shooter bases look ready for business.