by KA101
Welcome to BGG & the House on the Hill, burning mirage.The FAQ specifically states that the Traitor must still roll to open the Vault.
http://www.wizards.com/default.asp?x=ah/faqs/hoth
Vault -- Does the traitor have to roll to open the Vault?
Yes.
Yes.
[edited to remove Event card joke, which may or may not have been enjoyable-KA101]