By now, most of the Uprising members had left Zeston, going on missions all around the world. Only a rare few were left at the Warlock Council headquarters with Kellian.
More than half the nobles were also left in Zeston for protection in case of attacks. The Castle that was only recently conquered was left at bare minimum defense; however, no one knew about that.
No one could have imagined that the Uprising would be careless enough to leave Zeston so soon. Even the enemies couldn't have predicted it.
It was just a move that no one expected, and that's why Lucifer was confident enough to think that he had time to take care of other matters in the meantime.
Zeston was going through a silence after the storm and wasn't at much risk of being attacked. Even the remnants of the Warlock Council weren't stupid enough to attack Zeston after knowing that twenty of their leaders were killed like weaklings by Uprising.