When Hao Ren and Vivian arrived back to the Naqdal base, the minions of the Mad Lord had gone.
A small team of the minions tried to cross the security perimeter of Naqdal but was repelled by the drones. After a brief fight, the drones destroyed all scouts of the Mad Lord within the range of fire while other festered monsters roaming further afield retreated. The drones, which were not equipped with gravitational trap, did not manage to capture the enemy scouts. The festered monsters got away.
But it was not a big deal because the Naqdal security perimeter covered a wide area. Those monsters were not close enough to pose a threat or know the situation of the base. They did not even see the scale of the base cluster. The drones had intercepted the enemy scouts at half a light year away from the base.