I have an odd keystone, but I can't find the tower! please help!
I don't think Spiritomb is catchable in black and white. You need to migrate or trade it.
(On this site there is no location for Black and White where spiritomb is catchable
You can't get Spiritomb IN Black and White, but you cant transfer it from SoulSilver, HeartGold, Platinum, Pearl or Diamond.
You cannot physically capture it in the wild, but, if you have over 10,000 Dream Points in Dream World, you may find him in the Spooky Manor.
Just go on GTS man. You can breed spiritomb (They actually have genders) so you can get them for practically anything as long as you dont run into those jerks who ask for Reshiram/Zekrom level 9 or under.
P.S. Please dont ever ask for that. It really clogs upi the web. Plus it makes me sad. Whimper.