The beeping from the waist symbolized a message from the Ghost Maid stationed within the Undead camp.
Early that morning, Kane chose to wait here for this siege due to the unusual circumstances surrounding it.
According to the information from the Ghost Maid, the lich leading this attack intended to make it a major offensive.
Even if the fortress couldn't be broken, the goal was to severely weaken its defensive forces.
At the very least, they aimed to harvest plenty of strong corpses and souls.
However, since the Ghost Maid had only just infiltrated the undead ranks, she didn't know the lich's detailed plan.
She could only gather that the powerful lich had long prepared for this attack.
This meant that unexpected events were bound to occur in this battle, possibly stripping the fortress of its advantages.
In this most critical moment, it was Kane's group's turn to make an entrance.
The battlefield maintained its tense stalemate, even as the beeping continued.
