Mustafar was filled with places for N4-X4 to infiltrate and use. That much was clear after they had infiltrated Fortress Vader and stolen priceless data. The details of this information had informed the droid of where to find old Clone Wars era factories formerly used by the CIS. They had already begun operations to kick start other factories on the planet but this one in particular was going to be its own degree of difficult.
While the Apex Contractor was skilled in their field, they were only a single machine. Furthermore the planet was under the control of the Sith. In exchange for a portion of their 'product' a Sith Acolyte was going to accompany Naxa on this endeavor. The machine of war and death was skeptical of how much use a single acolyte could be but they reserved their calculations for when they had more data.
For now, N4-X4 waited in the shadows of the volcanic planet and watched a large canyon like crevasse for signs of activity. Hidden underneath the surface by both time and design, there lay a control core capable of producing hundreds, even thousands of war machines. However the facility had not received resources from off planet. Any droids inside could still be fully operational but were limited with only local sources of materials.
They would approach on foot unless this acolyte had a better idea. The BX commando droid waited patiently in secret and silence for their partner in this endeavor. Hidden by the heat, the darkness and their own scatterweave armored chasis they would be almost impossible to find. That was why they kept a photoreceptor out for this Sith acolyte. It would be more likely for Naxa to spot them than the other way around.
@Akheron