The droids started off near the hangar and the Rebels needed to get Artoo and at least one other character to the Falcon to win (they needed to transport the Death Star plans to Yavin IV). The Imperials could not harm the droids. Vader started on a tile near the hangar but was prohibited from taking any role in defending the hangar until he defeats Ben. In the event, that wasn't required, but he handily aced Ben anyway (I think Frederick rolled two "20"s in the combat and Ben whiffed with "1"s).
|"If you strike me down, I shall become more powerful than you could possibly imagine"|
|Oh crap, didn't think he was really gonna do that...|
|"They went that way! Get 'em!"|