After that detour, the Sith artifacts that were collected were put in the ship to be taken to Dathomir when they left. Rather than taking the same way out, they took a slightly different route. No idea what they could find. When they enter back into the tombs, Vader feels something... off. Like there was a gap in the force. He waves to his students. "Head back to the ship. There is something I must look into." Leaving his students, he wanders through the corridors, following that empty feeling. He finds a moderately large room with a stone coffin in the centre. Surging forth from the stone, odd, glowing, dust like particles come and coalesce to make a familiar form. "Darth Bane."
The Sith Spirit before him is large, and looms over Vader, studying him. "You know who I am."
Vader nods. "I do. You made the rule of two."
Darth Bane seems prideful. "And my name lives on, eons after. Tell me, have you come to be my apprentice?"
Vader shakes his head. "No. I have my own matter to attend to. I don't have time to be an apprentice." Vader considers his next words carefully. "I know what happened on Malchor. I found your personal holocron."
The ancient Sith scoffs. "And you have come to ridicule my weakness."
Vader shakes his head once more. "I wouldn't dream of it. I actually found the effort commendable."
Darth Bane seems in genuine shock. "What?"
Vader continues. "I myself am I the middle of a similar endeavour. I have established an Empire, and I plan to use it to help people." He looks up at the undead Sith. "Perhaps we could help one another."
Darth Bane is intrigued. "How?"
"Well, ancient knowledge of Sith culture is something the galaxy is unfortunately lacking. And I could always use a Dark Council at my side."
The ancient spirit is silent for a moment. "...My spirit is bound to my armour." When Vader boarded the ship, he had an ancient helmet under his arm.
They give the artifacts they found to the archivist and the droid helpers they have for cataloguing and the Acolytes go off to tell their friends stories about what happened. Meanwhile, Vader enters the empty council chambers at the top of his temple spire and places Darth Bane's helmet on one of the chairs. The ancient Sith Spirit forms from glowing dust coming from the helmet. He looks out a window to inspect the activity below. "You have done away with my Rule of Two."
Vader looks over his students. "I prefer my Rule of Many. I will protect them with my life."
Bane's mood turns solemn. "I once had such ambitions." He lays a hand on the glass. "So much like Malachor." He turns back to Vader. "What are your plans?"
"I want to re establish the Sith in the galaxy, not as warlord or tyrants, but as warriors, protectors. Unfortunately, there is a very specific obstacle in my way. A man by the name of Darth Sidious. He has... other ideas."
Bane glares. "What kind of ideas?"
"The Rule of One. He wants everyone, all force sensitives, to serve him and only him for all eternity."
Darth Bane narrows his eyes at Vader. "How do you know of this?"
Vader sits down in a high back chair of black stone. "That is a long story."