Crystals
The sphere cannons were prepared at various spots around the city wall.
Even though they are mostly automatic and are controlled by the spirits that are enchanted to it, Sam still has basic control of them.
He activated the sphere cannons and moved the barrels a bit so that they would be at a specific angle when they are shooting at the wolves.
Currently, eight cannons on each side of the wall are aiming at the wolves.
Sam sat on one side of the wall as he took out an inscription pen and started drawing something on the spheres.
These are neutral energy spheres and he is drawing inscriptions at a rapid pace. It took more than three minutes to complete one and he had to draw those inscriptions on eight spheres for each wolf.
It took more than two hours for him to be done with all of them and in these two hours, there are a bunch of undead hives that are shot over.