A Secret Weapon from Historical Fantasy

Talented MOC builder from Germany, markus19840420 shared recently this vignette with unusual medieval age weapon MOC, a huge balista in his flickr.com photo-stream. This MOC was built as a free built for the medieval fantasy RPG "Die Neun Reiche" in Imperium der Steine Forums. Actually I wonder a little bit who could draw a bow this size because the drawing mechanism stand in a position much higher than a minifigure can reach. My best guess will be a giant or troll could be able use this huge weapon.