Thunder Talons

The members Artificers Guild in Macarish are known for being extraordinary geniuses, but few stand up to the intellectual might of Xeckes the Pontificating Exarch of Extirpation. Renowned for his many peculiar creations, Xeckes is also known for some of the most impactful innovations of the current era. One such invention is the Thunder Talons, a defensive emplacement that is housed in most major cities.

Modern Uses

Thunder Talons are large mechanical ballistas able to store lightning within the bolt. These defensive emplacements consist of two major parts. A large lighting rod is able to absorb lightning strikes and distribute them to the connected ballista bolts. As well as a large metallic ballista designed to be rapidly loaded.
Macarish was the first city to adopt Xeckes’ inventions by deploying them along The Great Bridges. Soon after large cities throughout the world purchased blueprints for these inventions and quickly adopted them. They are rarely ever fired but are a necessary deterrent towards city attacks. Many cities on the outskirts of the world have been known to use them on large monstrous beasts that attack the city's walls.

Invention

For years Xeckes has attempted to harness the powers of Sarcool, the God of Storms. However, many of these inventions found no such luck, either unable to channel electricity or unable to keep it stable. This all changed during one of Xeckes' retreats to The Eternal Storm. Xeckes discovered a certain series of runes that were able to successfully store lighting within wrought iron.
Xeckes spent the next several months seeing how much lighting can be stored as well as how to expend its power. This series of runes was able to store within them a single strike of lightning for up to a month before needing to be defused. Xeckes also learned that the shape of the iron did not matter, just that it was at least 3.218 lbs. 
From there Xeckes returned to his laboratory in Macarish and carefully crafted lighting rods that were able to channel the storm into multiple ballista bolts. These bolts needed to be stored carefully but when fired they would explode with the force of a lightning strike. When he presented this invention to the public it was quickly adopted as a form of citywide defense.

I saw one fired once. It was terrifying. A flash of blue before a deafening blast. All that was left of the poor chap was his arms, still holding onto the rocks he was climbing.
~Eyewitness Account