The ballistae released loud explosive sounds, as not the bolts but rather the springs shot out of the siege engines, and it wasn't just one was all twenty and all three slings that could fire a bolt.
It completely took the soldiers by surprise, and many of them paid a heavy price.
The springs shot out and pierced through the bodies of the soldiers, there was so much tension in the springs that it crumpled their armour and wounded them seriously, and for many that wasn't the end, in their surprise they back away and slipped of the walls, falling to their deaths.
"Did you plan that?" Izlandi whispered to Lirian while everyone was still distracted.
'I rigged the weapons' she heard Lirian say into her mind, 'But as for the deaths, that was beyond my wildest imagination,' she heard Lirian laugh in her mind.
'By my sacred name, that has got to be such a humiliating death, death by spring,' Lirian mused with tears forming in the corner of his eyes.