If it is actually a Thundurus-EX card, then I think it is part of the Black & White Black Star Promo set which may have been released during the Plasma Freeze expansion. I think I have found a checklist, but since I am not really confident, I rather review it with someone before I upload it. I would want to create a good checklist so others wouldn't have to fix something that I break.
I am one of the members that helps within the site. I work closely with the IRs and can answer most questions. Please send me a message if there is anything I can assist with. If I don't know, I can certainly try to figure it out or direct you to a resource.
