When the elemental cannonballs hit those living bone towers, they can disperse the black mist in the surrounding area of hundreds of meters, exposing everything in the face of the city defense maze.
Until the skeleton army covers this place with new living bone towers, it will remain an undead forbidden ground.
The most destructive, naturally, is the Holy Light cannonball composed of positive energy, instantly knocking down all ordinary undead at the impact site.
As for why there are five types and not six, those few elemental cannons that launch negative energy cannonballs naturally cannot be used.
These negative energy cannonballs not only fail to cause any harm to those undead but instead heal them.
Yet, the black mist quickly surged up, engulfing everything around, including the various elements launched by the elemental blast cannons.
Only faintly can their fighting sounds be heard below, lasting a short time before disappearing.
