A Night in Serispron

You play as Marius, a master necromancer sent to the medieval fantasy city of Serispron by their Dark Lord. Their aim is to raise an army of undead from the massive crypts beneath the city to attempt an interior siege so his war on the mortal realm can begin. The catch? It has to be done in one night, so time is of the essence. The Dark Lord does not tolerate distractions.