Polish 9-barreled flintlock musket : Damned scary, heavy monster to be trecking through the woods!
Unlike the full-sized ballista which was a siege engine firing stone balls, the scorpio supported Roman infantry on the battle field by firing bolts at enemy. Description from pinterest.com. I searched for this on bing.com/images
A catapult which works like a ballista.
Trebuchet (working) model step by step free plans and instructions
Trebuchet | Siege Weapon
springald catapult | ... was the most popular siege catapult used during the medieval period
Siege Battering Ram