Where can I find the offical rules to the Dominion promo cards
http://wiki.dominionstrategy.com/index.php/Promo. This page links to all promo cards, each page quotes the official FAQs. Note that there are no special "rules" associated with the promo cards, in general what you need to know to play them is on the card text. But there are official FAQs/clarifications, like there are for every card. They should have come on a sheet with the cards themselves.