Design: Enchanted Ballista [3+1-1, 5+1-1, 2+1-1]
The enchanted ballista is rather ambituous; we've never enchanted something so big before, nor with so many spells at once.
The first enchantment attempted was a varient of Gust of Wind our Researcher Priests call "Boost of Wind". Essentially the ballista sucks in a blast of air before firing that travels along with the payload, decreasing air resistance and allowing it to travel further. This puts it into "Extreme Range" - the edge of being able to fire at targets in our line of sight. Beyond this distance we will likely need spotters to accurately hit our targets.
The second enchantment attempted was Lucky Strike, but unfortunately we ran out of time developing this one. Lucky Strike can still be cast by a mage separately, thankfully. Worryingly, however, accuracy has begun to drop off at Extreme Range even with Lucky Strike - our projectiles land within a couple meters of their intended target. It's still impressively accurate, but we can no longer pin-point snipe enemies at such a distance. It's likely due to the variance in speed caused by the fickle winds; in some cases the oiled canvas on our Firestorm Shells will be blown out before launch, sending a much less harmful clay pot sailing towards the enemy. Finally, the enchantments have a tendency to fade after a few days, requiring a mage to rebless the seige weapon periodically.
A side note: we are close to the maximum possible range we can achieve with the ballista. With some more tweaks we might be able to push the range another degree further afield, but the limitations of the weapons design will likely make further than that difficult.
Enchanting is relatively Expensive.