Wow, that must have been a spot-on shot there. Nice hit on those mercenary spearmen, who are probably, by the way, my favorite mercenaries because of effectiveness and looks.
The ballista was reasonably close, but it was actually hitting about 1 in 2. I started with about a quarter of its ammo remaining, and by the time it had finished it had a gold chevron - at which point it was hitting with every shot I saw.that must have been a spot-on shot there.
It got over 150 kills, I'm guessing at least 120 of them came from the last quarter of its ammunition since it chewed through 3 infantry units, with the remnants routing.
I'd considered ballistas to be pretty crap - I think this one was built by an AI governor - but I'm impressed with their ability to cause damage, even if I was abusing the passive AI.
The fire ability of catapults and billistas makes them way too powerful