The Dragon Vault Pokemon Cards expansion was a promotional expansion which was not legalized for actual tournament game play until the 15th of October. People where worried before the release because of such a major change of card style just before the Premier Tournament. The Dragon Vault expansion was released October 5th, 2012. An extra card was added to the English set of Dragon Vault. The extra card was considered a secret card and it was a Kyurem that was given as a promotional card in Japan.
Error Card Information:
The only error card known is the Exp.Share card was printed without the pokemon tool Rule.
Dragon Vault Pokemon Card Prices