13. What if you kill Six in Oculus beforehand, so that he isn't around to stop you from stealing the Mysterious Orb?
From the wiki, it looks like he's invulnerable to damage:
http://www.underrail.com/wiki/index.php?title=SixNo idea if he has the same bug as The Beast that lets you Expose Weakness him and then kill him, though.
14. He's immune to Electrokinetic Imprint and TNT while walking to the elevator.
15. You can successfully stop his pathing with a force field, molotov, or exothermic aura. But when the map transitions into the DC elevator, he still teleports in.
16. Locus of Control and Exothermic Aura expire during the conversation so you have no chance to kill him or be immune to his stun while in the dialog.
17. Here's a dialog inconsistency: If you drop the artifact at your feet while in the elevator, it will be dragged up with the elevator with you. However, Six will comment that the Faceless picked it up even though it was with you along.