Although constantly pelted and fired at with all sorts of projectiles, the undead did not stop their movements in the least, with the retractation of grounds units, the livings had granted their enemy much more flexibility in their movements, although the emerald light, spells, bolts and arrows were also problematic, enough that some rank and file had been defeated despite the overall power used to attack them wasn't the maximum- Despite that, the undeads still managed to erect outposts and camps beyond the dark keep, and even some small forts made from the same black stone.
The construction of such architectures was remarkably swift, as the mad architects of the empire had figured out ways to pre-build their creations somehow, made them into small cubes and then, only a simple activation was needed to make the building or assortment of buildings just spawn out of thin air.