The Skeletons in that first wave were just cannon fodder that Zhao Fu had sent over to see what the player army was up to. The true Skeleton army was the one coming now.
The black magic formation wasn't the Undead Disaster: It wasn't a summoning formation but a support-type formation. This formation gave the Skeleton army powerful attack, defense, and recovery, and the formation also boosted the Skeleton army's disaster attribute.
With this black magic formation, the true might of the Undead Disaster could be unleashed. The black magic formation fused with the Disaster King Ring's power, which was the fusion of the Undead Disaster with boundless disaster, creating the ocean of black bones below.
"Hurry and fire!" the commanders immediately yelled when they saw the countless black Skeletons rushing over like a black flood, their voices filled with fear.
The countless dumbfounded players quickly came back to their senses and shot their arrows.